European Journal of Personality, Vol. 4,259-286 (1990)
A basic information psychological parameter (BIP)for the
reconstruction of concepts of intelligence
SIEGFRIED LEHRL
University of Erlangen-Nurnberg, Erlangen, FRG
and BERND FISCHER
Fachklinik Klausenbach, Nordrach, FRG
Abstract
Adherents oj” the Galton paradigm favour the concept that the simple parameter ‘speed
of information processing’ has a physiological basis and determines complex achievements assessed in intelligence tests as well as social success. These assumptions are
supported by inter-individual correlations. Further supporting evidence comes from total
measurement where not only the information content of the stimuli is measured, but
also the time to process them. This reveals an individually constant period during which
1 bit of information is processed. It is called the ‘basicperiod of information processing’
(BIP), which lasts 1/15s (= 67ms) in average adults ( I Q 100) and is constant over
the ranges from which target stimuli can be drawn and over varying modes of the
signs (letters, numbers, musical notes, etc. ). In representative samples of adults duration
of BIP correlatos with global ZQ (r = -0.60): We conclude that the BIP of an adult
with an IQ of I22 is 50ms and with an ZQ of 78 twice as long (looms). We consider
BIP to be a physiological and general determinant of intelligence, being measurable
at a ratio or even an absolute scale level. Thus, it appears to be suitable as a building
unit for reconstructing the rather fuzzy traditional concept of general intelligence.
RECONSTRUCTION OF A COMPLEX CONCEPT
Many psychologists will agree that the concept of intelligence is important but difficult
to grasp in all its complexity. Therefore, it is necessary to search for more precise
and simpler concepts. One possibility is to attempt a reconstruction of intelligence
using elementary variables. It seems worthwhile to reconstruct this fuzzy and complex
concept using basic variables as building units, which are easier to grasp than the
complex concepts to which they belong. If it can be shown that this reconstruction
Correspondence concerning this article should be addressed to: Dr Siegfried Lehrl, University of ErlangenNurnberg, Department of Medical Psychology, Schwabachanlage 10, D-8520 Erlangen, FRG; or to Professor Dr Bernd Fischer, Fachklinik Klausenbach, D-7618 Nordrach, FRG.
0890-2070/90/040259-28$14.00
0 1990 by John Wiley & Sons, Ltd.
Received I 7 December 1987
Accepted 3 January 1990
260
S. Lehrl and B. Fischer
approximates the original concept of intelligence, its scientific value and applicability
will increase.
First, we will present current views about the speed of information processes that
may underlie intelligence. Then we will describe the measurement of mental processing speed by the methods of information-processing psychology. In particular, we
will present a parameter that can be understood as a ratio or even as an absolute
scale. This ‘parameter may not only provide a quantitative basis of intelligence but
may also contribute to the understanding of the structure and function of information
processing itself. Thus, we offer new empirical evidence for a simple biological basis
underlying intelligence.
INFORMATION PROCESSING AS A BASIS OF INTELLIGENCE
Information processing as a simple determinant or constituent
The possibility of reconstructing the concept of intelligence by only a single variable
was envisaged by Galton (1892) and was re-emphasized by Eysenck (1967, 1983,
1986a) when he suggested the usefulness of reaction time as an elementary and relevant measure of intelligence.
The measurement of reaction time is one of the oldest methods of experimental
psychology. It was introduced by von Helmholtz (1887) in 1850 to measure the
speed of nerve conductance. Donders (1868) used the same method to determine
the speed of mental processes. About the same time, extensive experiments were
conducted by Merkel(1885), the re-evaluations of which led to two important developments, one initisted by Hick (1952) and the other by Frank (1959).
Hick (1952) showed that reaction time (RT) increases additively with the information content H (bit) of items M but not with their number: RT = A + B x H(M),
where A is the intercept and B is the slope. Roth (1964) conducted experiments
on the relation between B, which is an individual constant, and global IQ. In particular, he showed that the slope (as the inverse indicator of information-processing
capacity) was lower in subjects with a higher IQ than in subjects with a lower IQ.
There are several other studies that are fully or partially in line with his results
(e.g. Carlson and Jensen, 1982; Cohn, Carlson and Jensen, 1985; Grice, 1955; Jensen,
1980; Jenkinson, 1983; Leonard and Carpenter, 1964; Smith and Stanley, 1983;
Spiegel and Bryant, 1978; Stabler and Dyal, 1963; Vernon and Jensen, 1984) whereas
only a few are not (Ruchalla, Schalt and Vogel, 1985; Smith and Stanley, 1980).
However, several of the studies mentioned have some limitations, such as selection
of cross-modal instead of uni-modal stimuli when determining the complex condition
in comparison with the simple one (e.g. Ruchalla et al., 1985), or lack of consideration
of restriction of range and the relatively high errors of measurement.
Following Hick (1952) and Roth (1964), the slope of the reaction time is interpreted
here as speed of information processing. This parameter may determine or constitute
the efficiency of other simple activities that are all related to global intelligence:
inspection time (Brand, 1984; Lally and Nettelbeck, 1977; Longstreth, Walsh, Alcorn,
Szeszulski and Manis, 1986; Nettelbeck, 1987), card sorting (Oswald, 1971), and
trail making (Reitan, 1959).
The Digit Symbol subtest of the WAIS and WISC intelligence tests is another
relatively pure test of mental speed. The so-called concentration test, ‘d2 test’, is
Period of information processing and IQ
Genetics
261
Cultural
Experience
BIOLOGICAL
INTELLIGENCE
Socioeconomic
status
PSYCHOMETRIC
INTELLIGENCE
disorders
background
Figure 1. Model of the relationship between simple determinants of intelligence, measured
by conventionaltests, and social intelligence (from Eysenck, 1986a)
in fact an intelligence test, as Westhoff and Kluck (1983) showed empirically: d2
correlates at around r = 0.60 with various intelligence tests in each of two studies
( N , = 89, N2 = 106). Even generating random numbers contains a component of mental
speed when the time for a single choice is limited to a second. Therefore, it correlates
moderately with global IQ (Dieminger, 1988;Waddell, Benjamin and Kemp, 1985).
Speed of information processing is hypothesized here to be the common denominator of all the above tests. In representative samples, correlations between these
simple tasks and global IQ vary within a wide range of r = 0.20-0.82. In favourable
conditions (with reliable measures and a full range of intelligence levels among subjects), average correlations of about 0.70 can be expected. For example, in seven
representative samples the Number Sequence Test correlated between 0.69 and 0.82
with global intelligence tests (Oswald and Roth, 1978). In summary, we conclude
that the overall correlation of speed of information processing with global intelligence
is substantial.
Intelligence cannot be claimed to depend on information processing on the basis
of correlation coefficients alone. Such correlations merely indicate that performance
on the different tasks of intelligence tests has something in common. It could be
a complex pattern of strategies at a high cognitive level or, on the contrary, the
effect of one simple variable ubiquitously participating in all performances. The
adherents of the Galton paradigm, as Eysenck (1983) called it, prefer the interpretation that a simple parameter speed of information processing determines or constitutes more complex mental achievements. In this sense, mental speed is not only
simple but also basic. Besides, it is arguably more intimately connected with biological
background than the complex tests which depend essentially on experience (see
Figure 1).
In the Galton tradition, we find not only theoretical evidence, concurring from
simplicity and closeness to physiological concepts, but also empirical findings promising to accumulate arguments in favour of the assumption that such variables are
not governed largely by a complex set of mental processes. Chase, Lyon and Ericsson
(1981) and Lyon (1977), as well as Egan (1986), indicated, respectively for memory
262
S. Lehrl and B. Fischer
span and inspection time, that the influence of strategies on some simple variables
was relatively small.
Information-processing analyses of cognitive performance
The possibilities which were hardly conceived of by researchers following the Galton
and Binet paradigms are (a) the joint total measurement of the stimuli and reactions,
and (b) time consumption during one and the same session. Take, for instance, the
following item of a conventional intelligence test: ‘Continue the numbers 1 2 4 7
11 16 22 . . .’. Even when taking into account the time necessary for a solution,
nobody can say directly how difficult it was.
The approach of Harwood and Naylor (1969), when determining the so-called
MIA (Maximum Rate of Information Acceptance) was very different. Their method
of testing enabled the subjects to present to themselves a stimulus which remained
as long as they kept a finely balanced switch depressed. The stimuli were digits
between 1 and 9 or numbers between 1 and 32 presented singly or in groups of
two, three, four, or five. By this procedure the time was measured until the signs
were perceived by the subjects. The information content of one digit of the repertoire
of nine possibilities was 23.17
= 9. That is, 3.17 bits. To recognize one of the 32
possibilities (= F ) was equal to 5 bits.
The MIA of 42 young university students (Naylor, 1968), was 21.4 bits per second
(sd = 4.9 bit/s) referring to the repertoire 1-32. The MIA for various adult groups
was as follows: for 105 ‘normal’ adults who were 60-69 years old, X = 14.2 bit/s
(sd = 3.4 bit/s); for 70-79 year olds ( N = 67), X = 12.9 bit/s (sd = 3.7 bith); and for
the 13 subjects aged 80+, X = 10.2 bit/s (sd = 3.3 bids). With digits (repertoire 1-9)
the means were similar (2= 23.5, 15.2, 13.9, and 11.7 bids, respectively).
Harwood and Naylor (1969) measured not only the time between stimulus and
reaction, but also the amount of stimulus information. This is the precondition for
the more striking observation that the results (in bit/s) are numerically equal although
the repertoires of signs differ.
The measurement of stimuli and reactions in terms of the information unit (the
bit) and physical time will only reveal properties of the subject if the following
two prerequisites are fulfilled: (a) the subject processes information in binary
decisions, and (b) the information content of the objective repertoire agrees with
that of the subjective repertoire. In the latter, the information is more precisely
called ‘subjectiveinformation’. More generally expressed, the pedagogically oriented
information psychology in Germany uses the term ‘subjective information’ to emphasize the information content of a message from a subject’s view. The more novel
a message, or the further its distance from existing knowledge, the greater is the
subjective information it contains (e.g. Weltner, 1973). As Shands (1959) stated,
this seems to be true for verbal and numeral information processing.
When a repertoire of signs (such as letters, digits, or numbers) is overlearned
in normal adults, independently presented signs-for example, the letters in the word
‘uenrd’ in contrast to ‘under’-have the same objective as subjective information
content. Otherwise, many of the experiments mentioned below could not have been
successful. The MIA registered by Harwood and Naylor (1969) is in a way an example
of a complete measurement, being composed of the following three essential parts:
(1) stimulus: complexity by subjective information content, presentation time
Period of information processing and IQ
263
practically zero, and therefore negligible; (2) reaction: complexity (releasing the
depressed switch) negligible compared with time of perception (in the case of more
than two digits); and (3) time between stimulus and reaction (minus motoric reaction
time), measured in ms.
The information amount being processed in a time unit seems to be constant,
and independent of the specific information content of a given stimulus (= nonspecific). This fact is confirmed by the almost equal absolute average MIA measured
by stimuli of different repertoires. The correlations between MIA determined by
numbers form 1 to 9 and MIA measured by numbers from 1 to 32 seem to be
sufficiently high if the high errors of the measurement of digits are taken into consideration [r(young adults) = 0.36; r(60-69 years old) = 0.68; r(70-79 years old) = 0.681.
Moreover, Hanvood and Naylor (1969) conceived of MIA as a fundamental capacity (in the sense of channel capacity) of cerebral data processing, which forms the
basis of more complex processes of perception and cognition.
Naylor and Hanvood’s experiment was not designed to see whether measured
capacity is independent of stimulus mode (visual, auditory, tactile, kinaesthetic, etc.).
Lehrl and Fischer (see section entitled ‘A general parameter’ below), however, have
demonstrated that MIA-related magnitudes are general capabilities.
Probably the key finding in the development of an intelligence theory from the
information psychology of perception was the substantial correlation between MIA
and intelligence-test scores in normal adults with an approximately representative
distribution of IQ [WAIS-full scale: r(digits) = 0.46; r(numbers) = 0.471. The highest
correlations were found with the WAIS subtest ‘Digit symbols’, which is the best
indicator of mental speed among all the WAIS subtests [r(digits) = 0.54;
r(numbers) = 0.521. (All correlations were significant at the 0.01 level.) A further
indicator of a relation with global IQ is the high MIA of the group which consisted
of young university students of presumably high intelligence.
Finally, Harwood and Naylor (1969) emphasized the proximity of MIA to biological
variables: According to them, MIA assesses relatively accurately the efficiency of ‘cerebral data processing’. What makes their results especially valuable from the point
of view of information psychology is that the data were measured at the level of ratio
scales. These features have many advantages for the establishment of relatively simple
theories of intelligence, and for practical applications, as will be demonstrated below.
There is one fundamental denominator of all the characteristics of Harwood and
Naylor’s (1969) work that explains a great deal of the variance and also the correlations with global IQ. It is already contained in MIA. It is the duration of the basic
period of central information processing (BIP).
THE INFORMATION PSYCHOLOGICAL PARAMETER ‘BZP’
Currently, there are several conceptualizations of the term speed of (central) information processing, and various corresponding lines of theoretical development. However, here we will delineate the conceptualization in the German informationpsychology tradition that is rooted in biological concepts.
The history of the psychological moment: from biology to information psychology
More than a century ago the biologist von Baer (1864), who is famous as the discoverer
of mammalian ova, had the idea that different species in the animal kingdom could
264
S. Lehrl and B. Fischer
be ordered in terms of the speed with which they process changing events. These
internal speeds were based on discontinuous psychical units of a certain length
(moving like the single frames of a film, as we would say today). He called these
units ‘moments’ and presumed that humans had six to ten per second, whereas
snails of course had distinctly fewer.
Wundt (1874), founder of the first psychological laboratory, took up this idea
and determined the human ‘moments’ as having a duration of 1/18 to 1/16 of a
second. The biologists von Uexkull(l928) and Brecher (1932) confirmed these values
and claimed their independence of specific sensory modes. Some typical examples
of their observations were that 18 acoustic waves per second cannot be distinguished
but are heard as a single tone, 18 single pictures of a movie give the impression
of a continuous movement, and 18 pinches per second on the same skin area are
perceived like one uniform irritation. Similarly, experiments with animals were conducted which led to relatively unequivocal conclusions about their genus-specific
moments. So, when snails were touched one to three times per second by a stick,
they suddenly moved back. But as soon as they were touched four times or more
per second they tried to creep on it, presumably because they perceived it as a
fixed object. Therefore, it was concluded that their moments last 1/3 to 1/4 s.
By a similar method, called ‘picture fusion’, Riedel (1966) demonstrated that the
moment shortens as children mature. By this method, which is explained in the
next section, he investigated children from 7 years (10 moments/s) onward to 15
years (15 moments/s). This latter value is consistent with those of average adults
(Lehrl and Fischer, 1988).
A simple measurement of the moment can be conducted by exchanging two pictures
like ‘I’ and ‘< ’. When inueasing the frequency of changes to more than 16 per second,
average adults form the impression of a ‘IS’.
Correspondingly, when slowing down
from a high change rate of more than 16 per second to about 14 changes per second
the impression arises that there is not one sign but two alternating signs. The mean
of the increasing and decreasing procedure is to be taken as characteristic for the
moment. For his experiments with children, Riedel used pictures such as two children
on a seesaw in two positions (Picture 1: left child up, right down; Picture 2: the reverse).
The children had to report their impressions: moving seesaw or two unmoved seesaws
forming a cross. It is remarkable that critical flicker fusion (30-50 Hz) has nothing
to do with the picture fusion (2= 15-16 Hz). This was demonstrated theoretically and
empirically by Weidenhammer and Fischer (1985). Their findings are affirmed by the
fact that picture fusion is related to intelligence, whereas, according to Jensen’s (1983)
results, critical flicker fusion has virtually no correlation with intelligence.
Frank (1959) noticed the numerical agreement between the duration of human
moments and the period in which 1 bit of information was processed. He called
it the ‘subjective time quant’, and thought its duration in adult humans to be 1/16s.
His concept was supported mainly by two information-theoretical analyses. The
first conclusion was drawn from Hick’s (1952) experiments, particularly from the
slopes that were obtained when the reaction time was related to binary information
content. Frank calculated 1/16s for the processing of 1 bit of information, presuming
that the decisions for the perception of the stimuli were as many as for the reactions
because the subjects had to recognize one of a certain number of possible stimuli.
In the next step, she/he had to find out the correct one of the same number of
possible reactions.
Period of information processing and IQ
265
The second confirmation came from an experiment by Miller, Bruner and Postman
(1954) which was called ‘recognizing letters of different redundancy’. At any one
time, they projected tachistoscopically groups of eight letters. The time of presentation varied between several 100 and l000ms. The strings of letters had different
redundancies. The authors selected four series with redundancies of 0 per cent (e.g.
YRULPZOQ), 15 per cent (STANAGOP), 29 per cent (WALLYOF), and 43 per
cent (RICANING). At each position of letters the percentage of correct recognitions
after a presentation was registered. The period for processing 1 bit of information
can be calculated when the time of presentation, the information content of a string,
and the percentage of correct responses are known. After the subtraction of the
redundancies the curves, which the authors published, were almost equal. Using
the slope of information increment per time in the range after the first 40 ms, Frank
determined the ‘subjective time quant’. It was about 1/16s.
Although the experiment of Miller et al. (1954) was based on language, Frank
never doubted the biological nature of the ‘subjectivetime quant’ because it originated
in physiological concepts. The numerical agreement between the duration of the
psychological moment, in which there was no inherent necessity to comprehend
it as the unit for processing 1 bit of information, and the duration of 1 subjective
time quant was striking. Nevertheless, why this connection exists was not theoretically
clear.
BZP the basic determinant of intelligence
Comparing the results of Roth and Frank, Lehrl(l974) presumed that the ‘moment’
during which, according to Frank, 1 bit is processed has to be shorter, the higher
is IQ. Empirical investigations to be summarized below have investigated this idea
(Lehrl and Erzigkeit, 1976; Lehrl, Erzigkeit and Galster, 1975; Lehrl, Straub and
Straub, 1975).
BIP is the shortest possible time during which a subject can process 1 bit of
information. In our account, the processing of information proceeds sequentially,
step by step. The necessity to process centrally two bits of information requires
two steps, three bits three serial steps, etc. The number of those binary steps is
determined by the stimulus itself and the subjectively activated repertoire to cope
with this stimulus. Therefore, the adjustment of the subject to the stimulus is extremely
important: The same number, for instance 7, has another information content, if
the subject expects a digit from 0 to 9 (3.3 bits) or a number between 0 and 31
( 5 bits) (see Figure 2).
BZP, which is a capacity, can be measured during the time of about 10 s of maximum
effort. Then the capacity drops. This was discovered while developing adequate
measures for serial activities such as reading letters (see below). In the range of
about lOs, there seems to be a series of time intervals of equal duration during
each of which 1 bit of information is processed. The maximal information processed
during 1 s was called the ‘capacity of information flow to short term store Ck’
(Frank, 1959): in other words, the maximal speed of central information processing
during 1 s.
Our first tests for the measurement of C,, in particular of BIP, were made in
a clinic with no funds for basic psychological research. Therefore, the materials
were restricted to paper, pencil, and a stop-watch. In addition, we were obliged
reaction
I
letters
1
2
3
4
5
6
bit
bit
bit
bit
bit
bit
Decision
1 bit
2 bit
3 bit
4 bit
5 bit
Decision
time o f adults
10 122 100
50
65
100 130
150
195
260
200
325
250
390
300
t i m e of a d u l t s
ia 122 100
50
65
100
130
150
195
200
260
250
325
(ms)
77
400
500
600
300
100
200
77
(ms)
400
500
300
100
200
0
1
2
stimulus A
3
4
r e a c t i an
5
stimulus 6
tna stimuli
6
7
1
9
.
reaction
8
numbers 0-9
.
.
.
reaction
two f i g u r e s
.
.
Figure 2. Models of information processing of different repertoires (‘letters’, ‘two stimuli’, ‘two figures’, ‘numbers 1-64’, and ‘numbers 0-9’).
The processes run in binary steps (measured in bits) from top to bottom. Therefore, it needs more decisions to process more extensive repertoires
(e.g. letters contain 5 bits of perceptual decisions until a reaction may be started) than less extensive ones, such as two stimuli (1 bit until the
reaction is possible). The magnitude which is connected with IQ in this way: The higher the IQ, the quicker the processing of 1 bit of information,
and the shorter the reaction times
REPERTORY
Period of information processing and ZQ
267
not to stress the patients, so the tests had to be short and uncomplicated and be
of some putative benefit to bedridden patients. Although under such conditions
we could not achieve as sensitive and precise a measure as under laboratory conditions, the important point was to meet the criteria for an information-psychological
approach, as outlined above.
With this aim, two tasks (‘letter reading’ and ‘number reading’) were developed.
Letter reading, which is described in the Appendix, consists of independent letters
that can be read aloud or silently. In the latter, it is established that the subject’s
sign for the beginning and the end is the raising and lowering of the thumb. The
time from the first to the last sound (or sign) is registered. This can be converted
to BZP or C, (see Appendix).
First, we discovered whether there were correlations with intelligence. This was
investigated in two small samples of adults whose IQs (vocabulary test) were distributed approximately normally (Lehrl et al., 1975). The one sample ( N , = 18; age:
46.9 f 10.1 years; 13 women, 5 men; IQ: 108.5 f 12.0) was psychiatrically normal.
The other sample (N2= 34; age: 50.2 f 11.0; 32 men, 2 women; IQ: 97.6 f 16.3)
suffered from endogenous depression. After adjusting for the influence of age, the
BZP of N , correlated with IQ -0.72. In N2 the correlation was -0.54.
These findings were replicated in a more extensive study (Lehrl and Erzigkeit,
1976) with 66 psychiatrically normal adults [age: 39.28 f 16.13 years; IQ (vocabulary
test): 99.30 f 16.06); r(BZP-IQ) = -0.701.
Thus, the relation with intelligence was confirmed (see Figures 2, 3, and 5). Meanwhile, more empirical studies have been conducted with different samples of psychiatrically normal adults with, in the large, representative IQs as measured by various
tests. All such studies support a substantial r(BZP-IQ). A review of these studies
carried out by different research groups is presented by Lehrl, Gallwitz, Blaha, and
Fischer (1990) (Table 1). The magnitude of the correlation between BZP and intelligence is generally about -0.60.
We have conducted far more studies of psychiatric patients than of normals, but
these results are not presented here because they depend on various additional conditions such as type and severeness of the disorder (Blaha, 1980). On the average,
the correlations of BZP-IQ obtained with psychiatric patients approach the level
of those with normals when the intelligence test is sensitive to acute psychical disorders. This is not the case, for instance, with vocabulary tests, which are mostly
insensitive to cerebral dysfunction. Vocabulary tests are therefore preferred for estimation of ‘premorbid’ IQ. The correlation between BZP and the results of such tests
for ‘premorbid’ IQ with psychiatric patients is lower than with normals (Lehrl et
al., 1990). Thus, we conclude that BIP indicates the momentary global or general
mental efficiency that is usually estimated by global intelligence tests which are highly
loaded with the general factor in the Spearman sense.
It is worth mentioning that several of our studies were contrived to find connections
between BZP and scores on tests which are variously related to intelligence (Table
2). The ten correlations between BZP and these test scores ranged from 0.52 to
0.82.
The backward-masked tasks used in many inspection time measurements give
further support for a relationship between BZP and intelligence. The average correlations across those studies between inspection time and IQ are substantial (Irwin,
1984; Longstreth et al., 1986). Even among university students (having restricted
268
S. Lehrl and B. Fischer
Table 1. All known studies on correlations between BZP,measured by ‘letter reading’, and
traditional intelligence tests
Sample characteristics
IQ
Age
Test
MWT-B-IQ*
MWT-A-IQt
MWT-A or MWT-B
CFTS
ZVTg
X
sd
-
X
sd
N
total
112.5
102.7
108.5
112.4
105.0
99.3
120.6
112.4
105.0
17.3
14.5
12.0
21.8
16.2
16.1
18.6
21.8
16.2
37.1
40.1
46.9
55.1
59.2
39.3
28.0
55.1
59.2
18.9
13.5
10.1
7.2
6.6
16.1
12.0
7.2
6.6
34 1
26
18
39
48
66
105
39
48
N
female r(BZP-.)
151
12
13
19
26
36
?
19
26
-0.57
-0.61
-0.72
-0.58
-0.60
-0.70
-0.29
-0.80
-0.5111
Nore: For further details, see the test manual by Lehrl et al. (1990).
* Mehrfachwahl-Wortschatz-Test-B (Multiple-Choice Vocabulary test, version B), serves the measurement
of the (crystallized)general IQ.
t Parallel form of MWT-B, see *.
$ Culture-fair-Intelligencetest, for (fluid) general IQ.
5 Zahlen-Verbindungs-Test (Trail-Making test), for (fluid) general IQ.
I(A few of these subjects possibly suffered from the beginning of an organic brain syndrome. The remaining
correlations are all based on psychiatrically normal subjects.
Table 2. Results of studies on correlations between BZP,measured by ‘letter reading’, and
tests for achievements which are variously related to intelligence
Sample characteristics
IQ
Age
Test
Reading words
Reading digits
The same 10min later
x
sd
108.5 12.0
97.6 16.3
?
?
x
N
N
total female r(BZP-.)
sd
46.9
50.2
10.1 Normals
11.0 Depressives
16to45
Normals
18
34
13
32
0.82
0.54
20
10
0.80
0.70
Saying opposites of read
words (black + white,
low + high, etc.)
The same 10min later
0.61
0.70
Counting symbols
112.4 21.8
105.0 16.2
55.1
59.2
7.2
6.6
Normals
Normals
39
48
19
26
0.59
0.55
Reading A for ‘B’ and B
for ‘A’(interference)
112.4 21.8
105.0 16.2
55.1
59.2
7.2
6.6
Normals
Normals
39
48
19
26
0.78
0.62
~
Note: For further details, see the test manual by Lehrl et al. (1990)
variance in intelligence) reliable tachistoscopic estimates of inspection time have
been claimed to correlate at around -0.40 with IQ (WAIS-R) (Stough and Nettelbeck, 1989). Furthermore, there are hints of an intimate relation between backward
masking and BIP. In the experiment of Longstreth et al., (1986), the efficient intervals,
Period of information processing and IQ
269
in which the exposed target stimulus had to be identified before it was replaced
by a masking stimulus, lasted between 34 and 84 ms. This, we know, is the range
of the duration of one BIP. In this experiment, the subjects were university students
and the subjective information content of each sign was not precisely defined: there
were four signs with different probabilities of presentation, and learning stages of
the subjects were different. Therefore, the information contents varied between 1
and 2 bits per sign. So, the interval contained more than 1, but less than 2 BIP.
It has been argued that BIP is related to more than intelligence when intelligence
is understood as a relatively constant state of mental efficiency. Guthke (1986) distinguished between tests of constant state intelligence and dynamic learning intelligence. He viewed status tests as measures of basic components of intelligence or
global IQ registering the state of an individual. Learning tests are more dynamic
and simulate the complex efficiency claimed to be a component of social intelligence.
He favoured the viewpoint that intelligence tests should be learning tests but he
could not avoid concluding that (p. 63 ff., translated by the authors): ‘In spite of
several theoretical and methodological objections against Frank and Lehrl’s initial
premises we confirmed the relations between the so-called basic components “speed
of information processing” and “short term storage” and results of state and learning
tests. Moreover, we found evidence for even higher correlations between speed of
information processing (measured by ZVT by Oswald/Roth [ 19781 and the reading
letters from the KAI/Lehrl) and learning tests than state tests.’
A general parameter
Biologists regard a ‘moment’ as a general property of a species because its absolute
length is largely constant and insensitive to different situations and to different
methods of operationalization. Correspondingly, the same should be true for the
‘subjective time quant’ and for BIP. However, for the latter individual differences
are emphasized as they are in many conventional concepts of information processing.
Whereas their generality is indicated by high correlations across different situations
and by different procedures, the additional particularity of BZP is that the results
of the same subjects should be numerically equal even when different methods are
used. That is, a person who is characterized by a BIP of 67ms by one method
of measurement should achieve the same BIP when another procedure is used (allowing for errors of measurement). This presupposes a constant level of motivation.
Accordingly, we set out to test this prediction. The subtests of ‘letter reading’
were appropriate for such a study because two of the four lines are written in small
letters and the other two in capitals. The different physical appearance should not
exert an influence on the time of reading, or on C,, or on BIP. This was investigated
in five samples of subjects, from which the best value of the two tests with capitals
was compared with the best value of the remaining lines [see Table 3; details in
Lehrl et al., (1990)l. As expected, different forms of stimuli did not influence the
results.
Another study was more ambitious (Lehrl et al., 1975; Lehrl and Fischer, 1988).
In addition to capital and small letters, values from 0 to 9 (digits) and 0 to 99
(numbers) were presented. The information content for letters = 4.7 bits, for
digits = 3.3 bits, and for numbers (0-99) = 6.6 bits. Responses were both silent and
aloud. An example of a line of numbers to be read was: 16 59 81 13 26 41 37
270
S. Lehrl and B. Fischer
0
4
8
12
16
20
24
28 bit/s
*Basic Period of Information Processing, i.e. the basic
period for processing 1 bit of information (ms)
Figure 3. Relationship between the amount of BZPs per second and IQ measured by the
multiple-choice vocabulary test MWT-B ( N = 672)
89 96 24. These different procedures were administered to 27 physicians, psycho-
logists, and postgraduates of the Erlangen University (FRG). The median values
agreed well. Capital letters aloud 22 = bitls, silently = 22 bit& small letters aloud = 23
bit/s, silently = 23 bit/s, numbers (0-99) silently = 23 bit/s. The average deviation
of the individual values across different procedures was 4-5 per cent, i.e. I bit/s,
and there was no significant deviation. However, this study has some limitations.
Speaking numbers aloud usually takes longer than perceiving numbers because they
have several syllables. Therefore, the results for reading numbers (0-99) aloud failed
to reach the level of about 22 bit/s. The same occurred with reading digits (0-9)
silently and aloud. Our preliminary explanation is: The digits' extent of repertoire
is so small (0-9) that the apperception time is shorter than the time consumption
of the reactions which are performed in parallel, such as speaking the digit vocally
or subvocally and turning to the next digit.
Another experiment for the investigation of the generality of BZP was conducted
12.2
16.2
21.8
105.0
112.4
10.2
98.8
94.7
10.9
95.0
sd
Note: For detailed data and sources see Lehrl et al. (1990).
*Basic version of 'letter reading'.
t Parallel version of 'letter reading'.
Outpatients
Brain syndrome
Questionable brain
syndrome
Without brain
syndrome
BZP (ms)
C, (bids)
Styrene-exposed
workers
Non-exposed controls
X
55.1
59.2
63.9
38.1
39.3
Sample characteristics
IQ
Age
7.2
6.6
7.9
10.3
10.1
sd
39
48
54
19
36
N
total
19
26
22
0
0
N
female
100.8
117.2
131.8
15.3
15.9
15.9
16.2
X
-
81.2
81.3
60.8
2.3
2.4
3.0
2.8
sd
103.7
118.3
134.2
15.0
15.2
16.1
16.6
X
92.8
85.0
63.0
2.2
2.4
2.3
2.8
sd
Reading letters
Capitals
Smaller letters
~
0.99*
0.98*
0.94*
0.83*
0.87*
0.85t
0.84*
r
Table 3. Comparison of results when C, (bids) or BZP (ms) are measured by signs of different physical appearance: letter reading of capitals
versus small letters
5
8
09
9'
2
2cb
2
6'
3
3
?
!
3
Q
.
6'
3
"a
272
S. Lehrl and B.Fischer
using ‘fusion of pictures’, ‘letter reading’, and ‘stimulus reaction time’ (specifically
double stimulus minus simple stimulus reaction time). These procedures were administered to 16 workers with lower IQs than the above-mentioned scholars. As expected,
their achievements were lower. The medians were: ‘fusion of pictures’ = 14 bit/s,
‘letter reading’ = 14 bitls, and ‘stimulus reaction time’ = 13 bit/s. The correlations
of ‘picture fusion’ with ‘letter reading’ = 0.70, with ‘stimulus reaction time’ = 0.69,
and with ‘letter reading’ = 0.40. These correlations are remarkable when considering
the restricted variance of the values and the high errors of measurement in all of
these procedures except ‘letter reading’ (see section on ‘Facilitating valid measurement’ below).
We now discuss the results of additional studies that show approximate numerical
agreements using further variables which are assumed to be an expression of BZP
(or CJ. However, with the exception of Harwood and Naylor’s (1969) study, these
demonstrations are not so convincing because their results concern only the mean
of one variable for a certain sample of subjects. Thus, connections between different
variables cannot be investigated. Moreover, IQ is often not reported, which is important for the level of BZP measure. As a guide for evaluating their results, university
students can be expected to have means of 18 bit/s and more, samples with average
education about 15 bit/s, and samples with lower education less than 15 bigs.
Harwood and Naylor’s (1969) measurements of MIA agree with these statements.
In accord with this are estimations of the speed of information processing in adding
and multiplying digits by adults. Both the speeds are about 14 bit/s (Lehrl and Fischer,
1988). Applying ‘recognition of letters of different redundancy’ to education students,
Frank and Wagner (1982) determined MIA to be 18-19 bigs.
Wenzel (1961) presented pianists independent musical notes out of a repertoire
of 17 possible notes. They were asked to play them as quickly as possible. Wenzel
registered the time required and calculated it to be 17.2 bit/s.
In his well-known experiments, Sternberg (1966) presented his subjects with up
to two dozen signs from a repertoire. These signs were digits, letters, or pictures
to be learned by heart. Later, he displayed one sign from the same repertoire and
subjects had to indicate as quickly as possible whether they had seen the sign before,
either by pressing a button or by responding verbally.
Sternberg’s experiments are comparable to those conducted by Oldfield (1966),
who found a linear increment of reaction time [RT (ms)] with the information content
(logarithmus dualis: Id) of the signs of a repertoire (M): RT (ms) = A + B x Id (M).
A symbolizes the intercept and B is the increment of the reaction time when one
sign is added to the repertory. This could be the BZP. In reanalysing a study by
Wingfield (1965) who asked his subjects, mostly university students, to search in
memory for pictures previously learned, Oldfield obtained the function RT (ms) = 373
58 Id ( M ) . Fifty-eight ms for one binary step of search corresponds to 1000/58ms
= 17.2 bigs. Briggs and Swanson (1969) conducted an experiment confirming
Oldfield’s results under the precondition that the repertoire was overlearned.
Other studies in the Sterberg paradigm, however, revealed an increment of reaction
times between 37 and 81 ms per scanning one item (e.g. Chapman, McCrary and
Chapman, 1981; Ford, Roth, Mohs, Hopkins and Kopell, 1979). Eighty-one ms
was found in old adults [mean 80.8 years of age, Ford et al., (1979)l and could
be a true value for 1 BZP for such subjects. On the other hand, 37ms seems to
be too short, even for average university students (cf. Table 5). Here confounding
+
Period of information processing and ZQ
273
effects might have occurred, such as finding out efficient strategies when scanning
more than two items, or not scanning exhaustively on positive trials. Confounding
effects of this kind are common in reaction time experiments (cf. Longstreth, ElZahhar and Alcorn, 1985). Therefore, in our measurement of reaction times we
limited the procedure to distinguishing between no more than two different signs
with no more than two responses (press the space key or not).
Studies about event-related potentials in the wake of the Sternberg paradigm seem
to reveal a scanning time per item even shorter than that indicated by reaction
times. According to the survey by Chapman et al. (1981), it varies essentially between
22 and 37 ms. This is too short for one BZP. Fortunately, Ford et al., (1979) published
their average results. For their six elderly subjects, ranging in age from 74 to 84
years (mean age = 80.8; WAIS mean raw score = 120, mean IQ = 130), the slope
was 27.5ms per item (digit). It was 27.4ms per item for their eight young subjects,
aged between 20 and 29 years (mean 22.8; WAIS mean raw score = 156, mean
IQ = 127). The slopes were averages referring to memory set sizes of 1 4 digits.
Positive and negative responses were mixed. When a subject reacts immediately after
a coincidence of a probe and a target item, the average holds when scanning 1.5
in two target items (always 1 probe item), 2 in three, and 2.5 in four target items.
If negative and positive responses are mixed with equal probability, the decisions
are 1 for one target item, 1.75 for two, 2.50 for three, and 3.25 for four target
items. An adequate correction would lead to a slope of 36.52mshtem in the young
and 36.61mshtem in the old subjects. It still seems to be too short to meet the
expectations for one BZP (Table 5). However, according to the diagram and rule-ofthumb calculation, the curves of Ford et al., (1979) show that the slopes from the
memory set size of 1-2 target items are the highest-about 40ms. The slopes from
two or three target items are zero or even slightly decreasing and to the end again
increasing, but less than from one to two target items. After two target items strategies
seem to be involved. When taking into account the positive responses, the slope
for ‘elementary’ scanning amounts to 53.3 ms. This result meets the expectation
for one BZP for highly intelligent subjects (cf. Table 5).
Even the control of one-dimensional manual movements towards a target maximally approaches 16 bit/s, respectively 1 bit per 60ms, as Stier (1969) found in
his experiments. The well-known findings by Fitts (1954) and Annett, Colby and
Kay (1958) on manual movements only resulted in 11 bit/s. But Stier corrected their
analyses and obtained about 16 bit/s for these experiments.
By and large, the assumption is supported that BZP is a general parameter. That
is, the calculated values are independent of the extent of repertoire of stimuli or
reactions, the sense modes or motoric modes mediating the information, and the
mode of sign (Figures 2 and 4). Furthermore, it means that BZP, according to the
information-psychology position, determines the speed of apprehending (apperception), associating (thinking), comparing, generating information, and scanning from
memory. Therefore, the time underlying these various components of information
processing is an indicator of the same underlying individual capacity.
A parameter at a ratio or at an absolute scale level?
The measurement by the information unit ‘bit’ and the chronological unit ‘second’
or ‘millisecond’ opens the chance to measure BIP (in particular C, ) at metric levels.
214
S. Lehrl and B. Fischer
Reading l e t t e r s o f alphabet s i l e n t l y ( s e r i a l
Reading l e t t e r s o f alphabet aloud ( s e r i a l 1
Recognizing numbers (1-9)
Recogni zing numbers (1 -32 1
Simple reactions t o m u l t i p l e s t i m u l i
Simple p i c t u r e fusion
Complex p i c t u r e fusion
Single l e t t e r s aloud
Reading music notes while p aying piano
Finding memory contents
v)
r,
c
9.
ID
a
r,
v)
Reading l e t t e r s o f alphabet s i l e n t l y ( s e r i a l 1
Reading 1e t t e r s o f a1 phabet a1 oud ( s e r i a1 1
Perceiving combinations o f e t t e r s
Recognizing numbers (1-9 1
Recognizing numbers (1-32)
Reading numbers s i l e n t l y (0-99)
Figure 4. Average values of mental speed expressed as C, (= BZPs per second). Mean performance of three subject groups in different tasks and studies. (The mixed groups comprise
a relatively high percentage of university students)
These units seem to model the psychological processes adequately. The agreement
of numerical results in bit/s obtained in different ways supports the assumption that
information is processed in binary steps.
Moreover, in the measurement of both information units and reaction times, an
absolute zero point is given. These two conditions define a ratio level scale. Since
an individual is characterized by an absolute number (e.g. 18 bit/s), it is even on
an absolute scale.
In order to appreciate this advantage of BZP consider the following example.
It would be legitimate to claim that the C, of a patient 3 h after a surgical operation
amounted to 60 per cent of his pre-operative value. In contrast, statements of this
kind are not correct for IQ, which is a parameter of frequency in a reference group
and not an individual measure.
The absolute point of zero also stresses that BZP is a basic parameter. Therefore,
we argue that BZP determines intelligence and not the reverse. This position is supported by the biological nature of BZP as indicated by the methods of its direct
psychophysiological measurement by picture fusion or reaction time that was shown
above. Subjects with a relatively long moment process little information per unit
time and therefore have many difficulties in solving problems in intelligence tests
(see Figure 5 ) or problems in daily life.
Facilitating valid measurement
Because the parameter BZPis a ratio measure, exact values count. A linear transformation of scores, which would be acceptable in correlation studies of IQ, can therefore
Period of information processing and IQ
BIP*
e
?
e
?
?
?
?
?
?
PROCEDURES FOR THE MEASUREMENT OF
INFORMATION PROCESSING
Inspection Time I T
Complex minus simple reaction time
D i g i t Symbol Test
Reitan T r a i l Making Test
dZ-llConcentrationll Test
Card Sorting
Choosing Random Numbers
67 ms
67 ms
67 ms
67 ms
67
67
67
67
67
67
67
275
ms
ms
ms
ms
ms
ms
ms
P i c t u r e Fusion
Maximal Information Acceptance M I A
recognizing d i g i t s
- recognizing numbers
Recognizing L e t t e r s o f D i f f e r e n t
Redundancy
L e t t e r Reading
- aloud
silently
Numbers reading s i l e n t l y
Memory Scanning
D i g i t s Adding
D i g i t s Multiplying
Double Mlnus Simple Reaction Time
-
-
*Basic Period o f Information Processing,
Processing 1 B i t o f Information.
i.e.
a
Basic Period f o r
Figure 5 . Subtest-neutral universality of duration of BZP and empirically confirmed correlations with global IQ. Drawn lines indicate already confirmed relationships. In contrast to
traditional information processing tests (with question mark), the subtests recommended here
allow BZP to be measured (mean 67 ms for IQ 100)
noticeably distort the results. We have several suggestions for avoiding irregularities
of measurement.
A general precondition for the measurement of the duration of BIP, as in any
other psychological efficiency test, is a well-motivated, alert subject. This has to
be emphasized because, for instance, resting EEG parameters which are registered
in an atmosphere of relaxation are frequently compared with results of psychological
efficiency tests. In this case, a good correspondence of electrophysiological and
psychological variables cannot be expected.
Subjects should be familiar with the signs whose information has to be processed.
Signs that are overlearned are useful, such as letters, numbers, or geometrical figures
(e.g. circles, crosses, and dots). The same is true for the mode of response. The
point is sometimes ignored in stimulus reaction time studies.
The subject has to be prepared for the repertoire of signs, (e.g. ‘You will see
digits between 0 and 9’, ‘numbers between 0 and 99’, ‘letters’). So that subjective
information content corresponds to objective information content. For example,
a number from the repertoire 0-9 has 3.3 bits (rounded off, 4 bits). However, within
the repertoire 0-99 the information content of the same number is 6.6 bits (rounded
off, 7 bits).
When evaluating the raw scores, the information content of the signs should be
rounded off because a subject can only perform full binary decisions. Therefore,
for one of the digits from 0 to 9 (3.3 bits) 4 full bits should be taken.
276
S. Lehrl and B. Fischer
The reliability of various procedures for BIP and ck differs widely. This is illustrated by the retests of 16 patients in a health resort after 24 h [mainly workers
suffering from obesity, diabetes, hypertonia, hyperuricaemia; nine females; age:
48.5 f 9.5 years; IQ: 101.3 f 12.0; more details in Lehrl et al. (1990)l: ‘Reading
letters measured by computer’: r(tt) = 0.51; ‘double reaction time minus simple reaction time’: r(tt) = 0.32 (best of each of the ten trials) and r(tt) = 0.13 (second best
of each of ten trials); ‘fusion of pictures’: r(tt) = 0.43.
Reading numerals (Weltner, 1987) or reading letters (Table 3 and 4) in paper-andpencil tests reach reliabilities on the level of well-accepted psychometric tests. Therefore, these are preferred for individual testing or research with small samples.
The most frequently used measurement for ck (particularly BIP) is letter reading
(see Appendix). For about 80 per cent of adults (17-65 years old) it seems to measure
BIP on C, without distortions. This concerns the middle range between IQ 80 and
120. Here the logarithm of BIP is normally distributed. Additionally, in this range
the agreement with other procedures to measure BZP is high (see section entitled
‘A general parameter’). Outside this range, however, distortions may occur which
can be caused by the methods and/or sampling errors due to the small number
of subjects with extreme values.
Between the IQ 80 and IQ 120 ck is distributed normally. Therefore, it is more
appropriate for correlations than BIP.
The resulting mean of BIP agrees well with the biological findings (1/15 s). Interindividually it varies remarkably in relation to IQ [ X = 67ms (IQ 100);
X - 1 sd = 83 ms (IQ 85); X 1 sd = 56ms (IQ 115); C,: 2 = 15.0 bit/s, sd = 3.1 bit/s].
Depending on differences in average IQ, there are also characteristic group differences
of ck (or BIP). So, the average value in adults is 15.0 bitls (sd = 3.1 bitls), in medical
students 20.2 bith, and in the mentally retarded about 9 bit/s or less.
There are several measures that are not adjusted to assess BIP or ck without
distortion because motoric components cannot be controlled. These include: (a) the
Reitan Trail Making test; (b) generating random numbers by Licklider’s procedure
described by Cherry (1957), as well as Wagenaar’s (1972) procedure; and (c) all
tests in which the repertoire of signs changes or refers to different sense modalities.
This last category includes one of the Naylor experiments where a combination
of numbers and letters had to be selected (Naylor, 1968), and some experiments
on complex stimulus reaction times (e.g. Ruchalla et al., 1985).
+
FURTHER FEATURES OF BZP
BIP is closely related to other indicators of speed of information processing and
therefore shares many of their characteristics. For example, Oswald (1981) obtained
correlations of between 0.40 and 0.50 between speed of information processing and
daily activities, such as personal hygiene and going shopping, of elderly persons.
In the same way, many correlations between biochemical and neurophysiological
parameters and speed of information processes or global intelligence obtained by
Weiss (1984, 1986, 1987) and Eysenck (1979, 1986a, b) are also valid for BIP.
However, new features associated with BIP are even more important. Most of
them depend on measurement at a high metric level. As a consequence, comparisons
with other human metric parameters are possible.
Period of informationprocessing and IQ
277
Table 4. Reliability coefficients of ‘letter reading’, basic version (if not otherwise marked)
Sample characteristics
IQ
Age
N
female
X
95.0
sd
10.9
X
39.3
sd
10.1
N
total
36
98.8
10.2
38.1
10.3
19
-
94.7
105.0
112.4
12.2
16.2
21.8
63.9
59.2
55.1
7.9
6.6
7.2
54
48
39
22
26
19
0.91
0.86t
0.95
0.86t
0.96
0.99
0.99
Intercorrelation of the
four ‘letter reading’
subtests
94.7
105.0
112.4
12.2
16.2
21.8
63.9
59.2
55.1
7.9
6.6
7.2
54
48
39
22
26
19
0.96-0.98t
0.99$
1.oo*
Immediate retests
100 female and male university students between
18 and 28 years
95.0 10.9
39.3
10.1
36
98.8 10.2
38.1
10.3
19
-
Specific reliability
Split-half*
Retest
8 h later
Retest
14 days later
Retest1
14 months later
-
102.7
14.5
?
?
40.1
66.9
13.5
9.4
26
144
12
86
?
?
65.7
9.5
182
87
71.9
12.8
59.8
9.4
130
75
r(tt)
0.81
0.86
0.88
0.62
0.94
0.9611
0.89
0.9611
0.70
Note: For detailed data and sources see Lehrl et al. (1990).
* r was calculated between the best of the first two cards and the best of the second two cards. Then,
according to Spearman-Brown, the correction formula was applied:
r’(tt) = 2 x r(tt)
1 + r(tt)
’
t Parallel version of ‘letter reading’.
$Calculated on the basis of the Spearman-Brown correction formula for prolongation:
r’(tt) = 4 x r(tt)
’
1 + 3 x r(tt)
8 r (original [German] version - Spanish version).
11 The values in the line above were taken on the 1st and 15th days. This r(tt) refers to letter reading
on the 15th and 29th days, i.e. 14 days later (always basic version).
1I (basic version - parallel version).
Integration with biological models of intelligence
Retests after minutes or months and even after more than 1 year (Blaha, Pater
and Lehrl, 1978; Lehrl et al., 1990) show that the maximum speed of information
processing remains relatively constant (see Table 4). Furthermore, it varies substantially among individuals. Because units of measurement are given, the coefficient
of variation by Pearson ( C V = 100 x dsd) can be assessed. CV of adults = 15 per
cent (Lehrl and Fischer, 1988).
C, or BIP varies more than most biological parameters published by Wechsler
(1935). To compare it: body length has a C V = 3-5 per cent and brain weight 8
per cent (Lehrl and Fischer, 1988).
278
S.Lehrl and B.Fischer
Because BIP is arguably fundamental, biological counterparts can be suggested
which reflect numerically comparable processes. In fact, Weiss (1986, 1987) refers
to electrophysiological correlations of intelligence to account for the quantitative
relations among basic parameters. He even considers the deeper microstructures
of time events, and regards BIP as a unit at a higher level. Although BIP seems
to be the elementary unit to process centrally one bit of information, the lowest
unit in the temporal architecture of mental processes may be the time-quantum T.
Geissler (1987) proposed T as an almost universal constant lasting approximately
4.5 ms, in which case BIP would always be an integer multiple of T. We will refrain
here from further discussion of more differentiated models of BIP.The combined
biophysical, physiological and information psychological conceptions, however,
appear to be suitable ways to give a new foundation for the psychology of intelligence.
Experiments with biological and information-psychologicalparameters registered
simultaneously from the same subjects will play an important role in the development
of these efforts. Neurophysiological variables, such as evoked potentials, are often
used without due consideration of the information content of the stimuli, the alertness
and motivation of the subjects, and the beginning of central processes at about
100 ms corresponding to BIP. Lehrl (1980) expects the basic rate of processing 1
bit in averaged evoked potentials to be in the wave after PI (postcentral: Wernicke’s
area and neighbourhood, speech-dominant hemisphere). The reasons are that (a)
the latency time between PI and P2 is the first interval to correlate with global IQ;
(b) it corresponds numerically well with 1 BIP;and (c) the simple stimulus reaction
time amounts to about 250 ms (minus about 60 ms for the basic decision stimulus
yes-no = 190ms, divided by 2; that is ca. 95 ms for the afferent and 95 ms for the
efferent branch).
Integration with information content of the environment
There is still another important advantage to knowing the individual’s basic capacities
for information processing. On the basis of this knowledge it can be assessed whether
and how an individual can master the informational aspects of hisker environment.
In principle, the assessment succeeds if the information content and the time of
presentation of the messages to be processed are registered. There are several
approaches to measure such messages which are understood to be sections of the
informational aspects of the human environment. The measurements mainly refer
to speech and book reading (Weltner, 1973). For instance, by determination of an
individual’s capability of information processing and the information content of
a text the necessary time for reading can be predicted. So, for example, an average
adult patient (C, maximally 15-16 bit/s) needs for apperception of each word of
drug instructions about 1s because empirical investigations have shown that the
subjective information content of each word of average drug instructions amounts
to about 16 bits. Because such instructions comprise 600-1000 words, the patient
will need 10-17 min (600-1000s) for reading only and this without deeper understanding.
In contrast to IQ, which is a parameter solely referring to performances of a
subject relative to other subjects, the basic cognitive parameters of an individual,
presented here, facilitate quantitative predictions of the individual’s dependence on
the information content of his environment. Moreover, quantitative (i.e. metric)
Period of informationprocessing and ZQ
279
models of complicated cognitive parameters and processes can be built on the basis
of the parameters presented here. This is particularly important because our society
is changing to an information society in which humans’ relatively low capability
to process information is being severely taxed. Therefore, Cobarg (1986) argues for
a psychologically founded system of strategies to cope with the affluent information
which he calls information hygiene. Mastering the affluent information technically
requires more knowledge of psychological moments and the information content
of the environment.
FURTHER ELEMENTARY COMPONENTS NECESSARY AND
POSSIBLE?
BZP correlates with global IQ approximately r = -0.60. This relation seems to be
strong because correlations of global IQ tests such as the WAIS and Raven test
are not much higher: f ( r ) = 0.65-0.75 (Wolfram, Neumann and Wieczorek, 1986).
But here the global IQ was measured by a vocabulary test which favours verbal,
i.e. sequential, binary processes. These, however, organize simultaneously presented
information which is typical for spatial tests such as the Raven test (Das, Kirby
and Jarman, 1975). So, they improve the efficiency to master these tasks remarkably.
This was shown by Merz (1969) who asked students to verbalize when attempting
to solve Raven test tasks. By this approach, their IQ improved 15 points. BZP is
the basic unit of analytic and sequential information processing, which seems to
be particularly intimately involved in concepts of intelligence. It is still unclear to
what degree BZP has to be supplemented by parameters of simultaneous and analogous processes in an attempt to reconstruct conventional concepts of intelligence
efficiently.
There is another basic parameter of intelligence and supplement of BZP which has
its own and relatively long history. It is the memory span (or immediate memory,
span of apprehension, duration of presence). As two empirical investigations show,
BZP and memory span together cover more of global intelligence than does each of
them alone. In the one case, r = -0.80 instead of r(BZP-IQ) = -0.70 ( N = 66) (Lehrl
et al., 1975); in the other, r = 0.67 instead of -0.57 ( N = 341) (Lehrl et al., 1990).
After accounting for the errors of measurement of each of the correlated variables
only little residual variance is left to cover additional aspects of IQ. The question
is whether there are any more components to consider for the reconstruction of
intelligence. Although for many practical purposes one or two elementary variables
may suffice to represent global intelligence, for more complete functional models
more variables need to be taken into account. Examples are the flexibility in shifting
from one repertoire of signs to another, or control of information processes, or
persistence. Unfortunately, these variables can only be measured on a lower scale
level than BZP. We can only hope that new ways will be found for measuring such
additional variables on a high quantitative level, too.
Much research still needs to be done on the information psychological concept
of intelligence presented here. Referring to BZP in particular, the concept and findings
may appear too simple in view of the sometimes strikingly inconsistent results (e.g.
concerning slopes in reaction time studies or slopes in the Sternberg paradigm).
We need to enquire whether investigations outside of the information psychological
280
S. Lehrl and B. Fischer
tradition have been designed with the necessary preconditions. However, the results
on the basic parameters of information processing demonstrate the possibility of
reconstructing the complex and sometimes fuzzy traditional concept of intelligence
by means of relatively simple, general, easily measurable, and precisely-defined basic
variables, which seem to be adequate for an integration with biological models.
ACKNOWLEDGEMENTS
We would like to thank Dr C . Brand (UK), Dr V. Weiss (GDR), Dr S. E. Hampson
(USA), and several anonymous reviewers for their comments on earlier drafts of
this paper.
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APPENDIX
How to administer the letter-reading task and derive a testee’s BZP
There are several measures for BIP or c k and-via these magnitudes-for the IQ. Among
all administered measures ‘Letter reading’ was developed as a test because it proved to be
sufficiently objective, reliable (Tables 3 and 4), valid (Tables 1, 2, 3, and 5; Figure 3), and
practicable (Table 4). Its acceptance by testees is high.
Letter reading consists of four cards (each 15 x 21 cm). In the middle of each card is a
line of 20 independent letters, having phonetically only one syllable. The size of each line
is 0.7 x 18cm. The first card in the German basic version of letter-reading follows. This
and all other cards may also fit the English administration.
u n r z t r f e p k b v ds n i 1 d m r
The subject is simply asked to read a series of mixed up letters in an undertone as quickly
as possible. Then he or she obtains the first card with the back upwards. As soon as the
testee has reversed the card and begins to speak, the stopwatch is started. The time from
the first to the last spoken letter is measured. It should be documented in tenths of a second,
e.g. 7.3 s.
If the subject has repeated one or more letters or has delayed for other reasons, he or
she is asked to continue even if there are mistakes. Then the next of three similar cards
with other letters is given. The corresponding German versions are
IPLZMBEOAEHIOAZTLEA V
mjztfrdsihdoltkgderi
ECXSBTLKEOGFDEA VIMHP
The total procedure takes about 1-3 min. Only the best time counts. When evaluating
the raw scores it must be remembered that a subject can only perform full binary decisions.
Therefore, the recognition of a letter out of the repertoire of 27 letters, which theoretically
has an information content of 4.7 bits ( 27 = 24.7), needs five binary decisions. Since each
letter contains 5 bits of information, the 20 letters contain 100 bits. This is divided by the
time of reading to obtain the amount of information processed in a second ck (bit/s). For
example, if the best time of a testee is 7.3 s, then ck = 100/7.3 (bit/s) = 13.7 bit/s. 1000 ms/Ck
equals the BIP (ms). In this example, BIP = 137 ms (and likewise, the ‘psychologicalmoment’).
By standardizing ‘letter reading’ on adults, normative data are available for BIP and c k
(Table 5). By Table 5 an additional allocation to IQ is also possible.
Although an exhaustive representative inquiry is still lacking, there are indirect estimates
Table 5. Normative data of duration of basic period of information processing (bip) and mental speed c k measured by the
test ‘Letter reading’
~~~
~
~
Percentile
IQ
BIP (ms)
c k (bit/s)
99.8
99.7
98.8
96.5
93.0
86.0
75.0
59.2
50.0
40.8
25.0
16.0
7.0
3.5
1.2
140
135
130
125
120
115
110
105
100
95
90
85
80
75
70
-41
-42
43-47
48-49
50-54
-55
5657
58-63
64-68
69-71
72-78
79-87
88-93
94-124
125-
25
24
23
21
19
18
17
16
15
14
13
12
11
9
-8
Period of information processing and IQ
285
of representative values: the parameter BIP (respectively c k ) was measured together with
scores on a vocabulary intelligence test which had been standardized on 1952 representative
Western German adults in 1974 [for further details see Lehrl et al. (1990)l. The sample consisted
of 672 adults (310 females; age: 42.7 f 21.1 years; IQ: 105.6 21.7). Within the range of
17-65 years no relevant relation with age was noticed.
Subjects in IQ intervals of 5 points (68-72, 73-77, 78-82, 83-87, etc.) were aggregated
and their medians in BIP and C, calculated. The results were the norms given in Table 5
and the regression lines in Figure 3. Because the connections are linear in the interval from
IQ 80 to IQ 120, Jeske, Lehrl and Frank (1982) suggested the following rule of thumb for
a quick determination of IQ. IQ = 5 c k (bith) 25; valid for 11 < c k < 19, i.e. 80 < IQ < 120.
As an estimate of the scatter, the standard deviation of C, was determined for the values
which are allocated to the (representative) IQ 115 and IQ 85. The resulting difference was
divided by 2. The result is f((ck) = 15.0 bit/s; sd = 3.1 bit/s. BZP: f = 66.7ms; sd = 19 ms.
The normative data in Table 5 are also valid for the parallel version of Letter-reading
which consists of the lines
df z k v b r x p l y t a s n d c o g h
LPHMOTVFRGSXEBAKMIDZ
n z kf v s c u 1 t p m a g x i r y b d
VTBURKZFCDPLMSENIXO Y
There are virtually no systematic retest effects, especially if the parallel version is applied
and/or if the interval between two measurements is large (cf. Lehrl et al., 1990).
Findings from Spanish speakers provide some evidence that the norms are valid for people
from different language areas (Carena, 1985). For Spanish, letters were omitted which are
spoken with more than one syllable (e.g. ‘w’), because in these cases speaking lasts longer
than perceiving and thus determines the registered time. Normally, as has been shown (Lehrl
et al., 1990), recognizing the new letter already begins while the previously perceived letter
is spoken, indicating a parallel process.
*
+
RESUME
Les adeptes du paradigme de Galton sont d’avis que le parametre ‘rapidit6 du traitement
de I’information’ a une base physiologique et qu’il joue un r61e decisif quant a I’accession
au succb social et a la realisation de performances complexes, cela ayant CtC Ctabli a I’aide
de tests d’intelligence. Ces assomptions sont Ctayees par des correlations interindividuelles.
Une autre evidence venant Cgalement les Ctayer provient des mesures totales oh I’on ne considere pas seulement I’information contenue des stimuli mais Cgalement le temps necessaire
a son traitement. Ceci a revCle qu’au niveau individuel, il existe une periode constante nessaire
au traitement d’une information d’un bit. On l’apelle ‘Periode de base du traitement de l’information’ (BIP), elle dure 1/15s (67 ms) chez une personne adulte moyenne (QI = 100) et elle
est independante de l’etendue du repertoire et du type de signe (lettres, nombres, notes de
musique, etc.). La dur6e de la BIP, dans des Cchantillons reprksentatifs d’adultes, corrklait
avec un QI global ( r E -0.60). On a par la suite trouve que la BIP d’un adulte ayant un
QI de 122 etait kgale a 50ms et que celle d’une personne ayant un QI de 78 Ctait deux
fois plus longue (looms). La BIP est consideree comme un determinant general physiologique
de I’intelligence qui peut 6tre mesure sur une Cchelle de niveaux ratio ou sur une Ochelle
de niveaux absolue. Voila pourquoi la BIP parait approprike comme fondement de la reconstruction du concept traditionnel piut6t imprecis d“intel1igence generale’.
ZUSAMMENFASSUNG
Die Anhanger des Galton-Paradigmas vertreten die Auffassung, daA der einfache Parameter
‘Informationsverarbeitungsgeschwindigkeit’
biologischer Art ist und daB er komplexe Leistungen determiniert, wie sie durch Intelligenztests oder durch den sozialen Erfolg erfaBt werden.
Diese Annahmen werden durch entsprechende interindividuelle Korrelationen gestiitzt.
286
S. Lehrl and B. Fischer
Weitere Bestatigungen ergeben sich, wenn eine totale Messung durchgefuhrt wird, das heibt,
wenn der Informationsgehalt von den Reizen ebenso wie von den Reaktionen gemessen und
auberdem die Zeit fur die Verarbeitungsvorgange erfaRt werden. Beim derartigen Vorgehen
kristallisiert sich ein individuell konstantes Interval1 heraus, in dem 1 bit Information verarbeitet wird. Es wird als Basiszeit der Informationsverarbeitung 'BZP' (= Basic Period of Znformation Processing) bezeichnet. Diese Basiszeit betragt bei Erwachsenen (IQ 100)
durchschnittlich 1/15 s (= 67ms) und ist unabhangig vom Umfang der Repertoires und der
Modalitat der verarbeiteten Zeichen (Buchstaben, Zahlen, Musiknoten, usw.). In reprasentativen Erwachsenenstichproben korreliert seine Lange mit dem Global-IQ ( I P -0.60). Die
BZP eines Erwachsenen mit dem IQ 122 dauert 50ms und mit dem IQ 78 doppelt so lang
(100 ms). BZP wird als biologische, elementare und generelle Determinante der Intelligenz
angesehen. Sie l a t sich auf dem Verhaltnis- oder gar Absolutskalenniveau messen. Deshalb
m a t e sie sich als Baustein fur die Rekonstruktion des relativ unscharfen konventionellen
Konzeptes der Allgemeinen Intelligenz eignen.