Brain and Language 101 (2007) 38–49
www.elsevier.com/locate/b&l
Electrophysiological and behavioral measures of the inXuence of literal
and Wgurative contextual constraints on proverb comprehension 夽
Todd R. Ferretti a,¤, Christopher A. Schwint a, Albert N. Katz b
a
Centre for Cognitive Neuroscience, Department of Psychology, Wilfrid Laurier University, 75 University Avenue, Waterloo, Ont., Canada N2L 3C5
b
University of Western Ontario, London, Ont., Canada
Accepted 3 July 2006
Available online 21 August 2006
Abstract
Proverbs tend to have meanings that are true both literally and Wguratively (i.e., Lightning really doesn’t strike the same place twice).
Consequently, discourse contexts that invite a literal reading of a proverb should provide more conceptual overlap with the proverb,
resulting in more rapid processing, than will contexts biased towards a non-literal reading. Despite this, previous research has failed to
Wnd the predicted processing advantage in reading times for familiar proverbs when presented in a literally biasing context. We investigate
this issue further by employing both ERP methodology and a self-paced reading task and, second, by creating an item set that controls for
problems with items employed in earlier studies. Our results indicate that although people do not take longer to read proverbs in the literally and proverbially biasing contexts, people have less diYculty integrating the statements in literal than Wgurative contexts, as shown by
the ERP data. These diVerences emerge at the third word of the proverbs.
© 2006 Elsevier Inc. All rights reserved.
Keywords: Proverb comprehension; Slow-cortical waves; ERP; N400; Late positivity; Self-paced reading
1. Introduction
Over the last decade researchers have begun to examine how people comprehend Wgurative statements when
they are placed in contexts that are consistent with their
Wgurative or literal meanings. One of the main goals of
this research is to understand the time-course in which
people construct Wgurative interpretations for statements
that could be interpreted literally or Wguratively. DiVerent theoretical accounts of Wgurative language processing
make clear predictions about the time-course in which
Wgurative meanings should be constructed. For example,
according to the standard pragmatic model (Grice, 1975;
Searle, 1979), people Wrst construct the literal meaning of
夽
This research was supported by a Canadian Foundation for Innovation (CFI) grant held by the Wrst author, and by separate NSERC Discovery Grants held by the Wrst and third authors.
*
Corresponding author.
E-mail address: [email protected] (T.R. Ferretti).
0093-934X/$ - see front matter © 2006 Elsevier Inc. All rights reserved.
doi:10.1016/j.bandl.2006.07.002
the complete phrase and only attempt to construct a Wgurative interpretation when that meaning is perceived as
inconsistent with the preceding context. Giora’s graded
salience model (Giora, 2003) posits that the most salient
or familiar usage of an expression, such as the nonliteral
sense of a familiar proverb, will be aroused at the initial
moments of processing regardless of the nature of the
preceding context. Other models, such as the direct access
models (Gibbs, 1995), and the constraint-based model
(Katz & Ferretti, 2001), are context-dependent and argue
that at the initial moments of processing the Wgurative
meaning of as statement is accessed at least as quickly as
the literal sense as long as the contexts are suYciently
constraining.
Results from studies employing on-line reading time
measures demonstrate that people do not take longer to
read a statement used Wguratively than used literally when
placed in contexts that strongly constrain for the Wgurative
interpretation, thereby providing support for models that
do not posit a delay in accessing Wgurative meanings
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
(e.g., Gibbs, Bogdanovich, Sykes, & Barr, 1997; Katz & Ferretti, 2001). Despite these Wndings, recent research involving
Event-Related-Brain-Potential methodology (ERP) suggest
that people have more diYculty integrating the Wnal word
of statements when they are intended to be taken as nonliteral statements rather than as literal statements (e.g., Coulson & Van Petten, 2002; Katz, Blasko, & Kazmerski, 2004;
Pynte, Besson, Robichon, & Poli, 1996). The primary brain
potential of interest in these studies has been the N400
component (Kutas & Hillyard, 1984). The N400 component is typically interpreted as indexing the ease of semantic
integration of words in context; words that are more diYcult to semantically integrate elicit an N400 with larger
amplitudes than words that are easier to integrate. The
results of the studies cited above show that, Wrst, negative
amplitudes that peak about 400 ms after the presentation of
the critical word tend to be largest for sentence Wnal words
when they are embedded in Wgurative compared to literal
contexts and, second, the N400 is often followed by a late
positivity, in which there is a larger positive amplitude for
words presented in Wgurative than literal contexts.
Researchers have interpreted these Wndings as showing that
conceptual integration is more diYcult for statements
intended to be taken Wguratively than literally (e.g., Coulson & Van Petten, 2002) and, because these diVerences
occur during the processing of the statements (Katz et al.,
2004), they cannot be accounted for by models that hold
that literal meanings must be processed prior to generating
a Wgurative meaning (e.g., Grice, 1975).
In the following research we build on previous research
in several ways. First, we measured ERPs when people read
familiar Wgurative statements presented in literally and
Wguratively biasing contexts. In our case, in addition to
examining N400 and late positivity eVects to single words
as above, we also examine slow-cortical wave brain potentials that develop over multiple words in sentences and
clauses. Previous research has shown that slow-wave potentials are sensitive to the ease in which people integrate sentences and clauses into a developing mental model of the
text (e.g., King & Kutas, 1995; Münte, Heinze, & Kutas,
1998). Ease in integrating sentences is associated with a
frontally distributed positivity which is sustained over the
sentences, typically taken to indicate decreased working
memory load relative to sentential structures that are
harder to integrate. Thus, in addition to providing a measure of working memory load, slow-cortical wave potentials are similar to N400 and late positivity components
found for single words in that they enable us to examine
when a critical statement becomes more diYcult to integrate with preceding contexts. To our knowledge, this
research is the Wrst to concurrently investigate both slowwave potentials that develop over sentences and single
word averages to provide converging indices on when and
how Wgurative statements are integrated in discourse contexts.
In this study we employ proverbs to examine the eVects
of contextual constraints on Wgurative language processing.
39
Proverbs are unique relative to metaphors or irony, the
most commonly studied forms of non-literal language,
because they can be regarded as generally true statements
both literally and Wguratively (e.g., lightning really doesn’t
strike the same twice). In contrast, a metaphor such as Children are precious gems, is true Wguratively but not literally.
One consequence of this property of proverbs is that when
a familiar proverb is placed within a context that invites a
literal reading, there is inevitably a greater degree of conceptual overlap between the target proverb and words in
the context than when the same target is placed in a context
that invites a non-literal proverbial reading. One might
expect that this diVerence alone would lead to faster reading times for familiar proverbs placed in literal biasing contexts relative to Wgurative biasing contexts in previous
research. However, Katz and Ferretti (2001, 2003) using
word-by-word self-paced reading methodology found that
people read familiar proverbs at the same rate whether or
not they are presented in literal or Wgurative contexts, and
whether or not explicit markers are employed to signal the
reader that an upcoming statement should be interpreted
literally or Wguratively.
2. Experiment 1
In Experiment 1 we use ERP methodology to examine
how people interpret familiar proverbial statements in literal and Wgurative biasing contexts. There are several
advantages to using ERP methodology. First, ERP methodology is well known for having a Wne temporal resolution. Second, individuals can simply read for
comprehension without having to push buttons to advance
through text. Third, ERP methodology provides insight
into the electrophysiological response of the brain to processing familiar proverbs. As discussed above, slow-wave
potentials, the N400, and late positivity components (LPC)
have all been shown to be a sensitive measure of when diYculties arise in integrating words and sentences in discourse
contexts. Moreover, topographic diVerences in brain potentials provide additional insight into how diVerent populations of neurons contribute to diVerences found between
conditions.
Our main predictions for slow-wave potentials and single word averages are similar. SpeciWcally, if people have
less diYculty integrating the proverbs in literal than Wgurative contexts due to greater conceptual overlap in the literal
contexts, then we would expect to Wnd more positive slowwave amplitudes at frontal locations for the literal than
Wgurative condition. The diVerence in slow wave amplitudes should begin at the point in which the literal condition becomes easier to integrate than the Wgurative
condition, and this diVerence should be sustained over the
proverbial statements. Based on previous research on Wgurative language processing (e.g., Coulson & Van Petten,
2002; Katz et al., 2004), we also expect to Wnd a smaller
N400 and a smaller LPC at the word(s) in the proverbial
statement in which people begin to have less diYculty in the
40
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
literal conditions. Alternatively, if the proverbial statements
are interpreted as easily in the two contexts, then we would
not expect to Wnd any diVerences in the ERP results.
Table 1
Mean norming ratings (on a 1–7 likert scale) for Wgurative and literal
paragraphs used in Experiment 1 and 2
2.1. Participants
Twenty-four participants participated in the ERP experiment and 99 students participated in the rating studies. All
participants were native English speaking undergraduate
students from Wilfrid Laurier University who received
course credit for their participation.
2.2. Materials and procedure
2.2.1. Rating studies
We Wrst conducted a rating study to ensure that our
proverbs were familiar to our population. Twenty-seven
participants were presented with 116 proverbs and were
asked to rate on a 7 point scale how familiar each proverb
was to them (1 D not at all familiar, 7 D very familiar). We
then selected 58 familiar proverbs (all seven words long)
that served as the basis for constructing our target paragraphs. For each of the 58 proverbs, we constructed a context that invited a literal reading and a context that invited
a Wgurative reading.
Each of the contexts had 4 sentences preceding each
proverb, and the sentence before the proverb was always
identical across the two contextual conditions. The contexts
were in narrative form and described interactions between
people (see examples 1a and 1b). For the literal biasing contexts we ensured that the content words of the familiar
proverbs did not appear in the contexts. This ensured that
any advantage found for the literal contexts could not be a
result of repetition priming between the words in the contexts and words in the proverbs.
(1a) Figuratively biasing context
“What you need is an investment to shelter your proWt”,
said Ann. “But it’s been a volatile market since the crash,”
replied George. “Look, I lost a lot of money last year.”
“Don’t worry, you’ll be alright,” she assured him. Lightning
never strikes the same place twice.” “How can you be certain?”, he asked. “Its true, the market goes in cycles; it
won’t crash again for years,” she replied.
(1b) Literally biasing context
“Let’s take shelter from the rain under this broken tree,”
said Ann. “But it’s dangerous to hide under a tree during a
storm,” replied George. “Look, the tree has been hit once
already.” “Don’t worry, you’ll be alright,” she assured him.
“Lightning never strikes the same place twice.” “How can
you be certain?,” he asked. “Its true, once the energy dissipates, it takes a while to rebuild,” she replied.
We then validated our stimuli with two additional rating
studies. In order to ensure that the proverbs were equally
comprehensible in the literal and Wgurative contexts, we
asked 48 participants to rate each paragraph for how easy
they thought the proverbs were to comprehend in the contexts (1 D not all easy to comprehend, 7 D very easy to com-
Ease of comprehension
Context Wgurativeness
M
SE
M
SE
.1
.1
5.5
2.3
+3.2¤¤
.2
.2
Figurative paragraphs 5.5
Literal paragraphs
5.3
DiVerence
+.2
¤¤
p < .01.
prehend). In the second study, 24 participants provided
ratings for how literal or Wgurative they thought the proverbs were in the diVerent contexts (1 D very literal, 7 D very
Wgurative). This rating study ensured that our contexts were
literal or Wguratively biased as claimed.
Based on the results of these rating studies we selected 32
proverbs and their corresponding literal and Wgurative
biasing contexts to serve as the experimental stimuli. The
mean ratings for these items are presented in Table 1. Overall, the items were rated similar for ease of comprehension
(t(31) D 1.15, p D .26), and the Wgurative contexts received
higher Wgurative ratings than the corresponding literal contexts (t(31) D 11.38, p < .001). Finally, the 32 proverbs were
rated relatively high for familiarity, M D 4.9.
The 32 proverbs were placed across two experimental
lists with the restriction that each participant read each
proverb only once and each proverb appeared in a Wgurative and literal context. Ninety-six Wller trials similar in narrative form and length were included in each list to create
an experimental environment in which all of the items
would be read in their usual manner, i.e., without inducing a
strategy to read for Wgurative meaning. Accordingly, none
of these trials included Wgurative statements. The low proportion of Wller trials relative to Wgurative trials is a control
that is missing from previous research investigating the
eVect of context on interpreting literal and Wgurative language. In total, only 25% of the paragraphs involved a
familiar proverb, in half of those trials the proverb was
used literally and in half of the trials the proverb was used
Wguratively.
Participants sat in a chair in front of a computer monitor located in an electrically shielded chamber. They were
instructed to read the words one at a time and to answer
periodic comprehension questions by pressing buttons
labeled “Yes” and “No”. The 32 Experimental paragraphs
and 96 Filler paragraphs were presented one word at a time
in the center of a computer screen. All words were presented for a duration of 300 ms with an SOA of 500 ms. The
Wnal word was always followed by 2000 ms of blank screen.
2.2.2. EEG recording and analysis
The electroencephalogram (EEG) was recorded from 64
electrodes distributed evenly over the scalp. See Fig. 1 for a
schematic diagram of the layout of the 64 channel cap and
the corresponding electrode labels. Eye movements and
blinks were monitored via additional electrodes placed on
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
41
Fig. 1. Schematic diagram showing the electrode labels and sites for the 64 channel electrode caps used in Experiment 1.
the outer canthus and infraorbital ridge of each eye. Electrode impedances were kept below 5 k. EEG and was processed through a Neuroscan Synamps2 ampliWer set at a
bandpass of 0.05–100 Hz, and was digitized at 250 Hz.
3. Results and discussion
The data were re-referenced oV-line to the average of the
right and left mastoids. High frequency noise was removed
by applying a low-pass Wlter set at 30 Hz. ERPs were then
computed in epochs that extended from 200 ms before the
Wrst word of the sentence to 1000 ms after the Wnal word’s
onset (i.e., ¡200 to 4000 ms). Single word epochs were calculated that extended from 100 ms before each word to
1000 ms following the onset of the words. Trials contaminated by blinks, eye-movements, and excessive muscle
activity, were rejected oV-line before averaging; 25% of the
trials were lost due to artifacts in the slow wave averages,
and 20% of the trials were lost in the single word averages.
We discuss the slow-wave analyses Wrst, followed by the
single word analyses.
3.1. Slow-wave averages (¡200 ms to 4000 ms)
Fig. 2 shows the slow-wave potentials for both contextual conditions at one frontal and one central/parietal electrode site (FZ, CPZ) located down the midline, and Fig. 3
shows the topographical distribution of the results for all
channels. As can be seen, the slow-cortical waves for both
contexts become progressively more positive across the
proverbs. However, at about the third word of the proverbs
the literal condition starts to become signiWcantly more
positive than the Wgurative condition, and this positivity is
sustained over the remaining words in the proverbs. The
observed diVerences between the context types were largest
over frontal sites, smallest over posterior sites, and had a
similar distribution across the right and left hemispheres.
3.1.1. Overall analysis
We conducted 3-way ANOVAs on the mean amplitude
for each condition at 7 separate regions of interest: one for
each 500 ms word region in the proverbs. The main factors
of interest were Context (literal vs. Wgurative) and Electrode Site, both of which were within participants variables.
List was used as a between participant factor to stabilize
any variance caused by rotating participants across the
diVerent lists (Pollatsek & Well, 1995). Table 2 shows the
results for each region of interest. All p-values in this and
subsequent analyses are reported after Epsilon correction
(Huynh-Felt) for repeated measures with greater than one
degree of freedom.
As illustrated in Table 2, there was no signiWcant main
eVect of Context and no interaction between Context and
Electrode Site at the Wrst two words of the proverbs.
42
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
Frontal (FZ)
-5.0
-2.5
0.0
2.5
µV 5.0
7.5
10.0
12.5
15.0
17.5
20.0
-200.0 300.0 800.0 1300.0 1800.0 2300.0 2800.0 3300.0 3800.0
-5.0
-2.5
0.0
2.5
5.0
µV 7.5
10.0
12.5
15.0
17.5
20.0
-200.0 300.0 800.0 1300.0 1800.0 2300.0 2800.0 3300.0 3800.0
ms
ms
Central/Parietal (CPZ)
µV
-5.0
-2.5
0.0
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
-200.0 300.0 800.0 1300.0 1800.0 2300.0 2800.0 3300.0 3800.0
-5.0
-2.5
0.0
2.5
5.0
µV 7.5
10.0
12.5
15.0
17.5
20.0
-200.0 300.0 800.0 1300.0 1800.0 2300.0 2800.0 3300.0 3800.0
ms
ms
Fig. 2. Experiment 1 mean amplitudes at one frontal site (FZ) and one central/parietal site (CPZ) located on the midline Wltered with a low pass Wlter set at
30 Hz (left columns) and at .7 Hz (right columns) to reveal slow-wave development over proverbs. The Wgurative condition is shown in blue and the literal
condition is shown in red.
+10.0
Figurative Context
+9.1
+8.1
+7.2
+6.3
+5.3
+4.4
+3.4
+2.5
Literal Context
+1.6
+0.6
-0.3
-1.3
-2.2
-3.1
-4.1
3rd word
4
th
word
th
th
5 word
6 word
th
7 word
-5.0
Proverb Region
Fig. 3. Topographical distribution of mean amplitudes in micro-volts at all electrode sites for each 500 ms word region starting at the third word of proverbs through the seventh word for Wgurative contexts and literal contexts.
However, at the third word of the proverbs, the main eVect
of Context was signiWcant—greater positivity was found
for proverbs located in literal compared to Wgurative contexts. From the fourth word through to the sixth word, the
interaction between Context and Electrode Site was signiWcant. At the seventh word, the interaction was marginally
signiWcant (p < .08).
3.1.2. Slow-wave distribution analysis
In order to examine the observed interactions between
Context and Electrode Site, we conducted a 5-way
ANOVA on the proverb regions in which the interaction
was signiWcant. In addition to the Context and List Factors
used in the overall analysis, we added Hemisphere (left vs.
right), Laterality (lateral vs. medial), and Anteriority
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
Table 2
Experiment 1 grand average (n D 20) slow-wave results for each of the 7
word regions (500 ms epochs) in the proverbs
Word
1st
2nd
3rd
4th
5th
6th
7th
a
¤
¤¤
Context
Electrode £ Context
F<1
F < 1.1
F(1,18) D 4.33¤
F(1,18) D 2.55
F(1,18) D 2.95
F(1,18) D 2.45
F(1,18) D 2.53
F<1
F<1
F < 1.1
F(61,1098) D 2.83¤¤
F(61,1098) D 2.49¤
F(61,1098) D 2.63¤
F(61,1098) D 1.96a
Table 4
Experiment 1 grand average N400 (300–500 ms) results for each of the 7
words in the proverbs
Word
1st
2nd
3rd
4th
5th
6th
7th
¤¤
D p > .05 < 10.
p 6 .05.
p < .01.
(prefrontal vs. frontal vs. parietal vs. occipital). All of these
additional factors were within participants variables. The
results of this analysis are presented in Table 3. We only
report the results for the interactions involving context
because those are the only interactions that are of theoretical interest here.
As shown in Table 3, the Context by Anteriority interaction was signiWcant at all regions examined with, in each
case, the mean amplitudes being more positive in the literal
compared to the Wguratively biased contexts at prefrontal
sites, all p’s < .002, and at frontal sites, all p’s < .001. In contrast, there were no diVerences between the two contexts at
parietal and occipital sites.
3.2. Single-word averages
3.2.1. N400 analysis (300–500 ms)
The results of the N400 analysis are presented in Table 4.
Fig. 4 shows the N400 at one frontal electrode (FZ) and
one central/parietal electrode (CPZ) located along the midline for the third word of the proverbs. Fig. 4 also shows the
topographical distribution of the amplitudes for the two
conditions in the N400 region for all electrodes. At the third
word of the proverbs, the literal condition was less negative
than the Wgurative condition, F(1,18) D 20.80, p < .001, and
this eVect of context interacted with electrode site,
F(61,1098) D 3.76, p < .01. No other main eVects or interactions for the N400 were found at any of the other words in
43
Context
Electrode £ Context
F<1
F < 1.25
F(1,18) D 20.80¤¤
F<1
F<1
F(1,18) D 2.47
F<1
F < 1.31
F<1
F(61,1098) D 3.76¤¤
F<1
F<1
F < 1.84
F<1
p < .01.
the proverbs. We examine the interaction between context
and electrode site in the topographical distribution analysis
reported below.
3.2.2. N400 distribution analysis
The same 5-way distribution ANOVA reported above
was also performed on the mean N400 amplitudes. The
results of this analysis are reported in Table 5. As shown in
the table, there was a marginal Context by Anteriority
interaction, F(3,54) D 3.56, p < .06. This marginal eVect
occurred because the N400 region was less negative for literal contexts than Wgurative contexts at frontal (mean
diVerence D 2.65 V; F(1,54) D 42.90, p < .001) and prefrontal sites (mean diVerence D 2.11 V; F(1,54) D 27.14,
p < .001) than at parietal (mean diVerence D 1.44 V;
F(1,54) D 11.02, p < .05) and occipital sites (mean
diVerence D .95 V; F(1,54) D 5.50, p < .05).
The interaction between Context and Laterality reached
signiWcance, F(1,18) D 4.51, p < .05. This interaction
occurred because the diVerence between Wgurative and literal contexts was larger at medial electrode sites (mean
diVerence D 2.02 V; F(1,18) D 136.74, p < .001) than at lateral sites (mean diVerence D 1.50 V; F(1,18) D 75.51,
p < .001).
Finally, the three-way interaction between Context,
Anteriority, and Laterality also was signiWcant,
F(3,54) D 6.06, p < .01. This interaction occurred because the
diVerence between the Wgurative and literal contexts at
anterior and posterior electrode sites was larger at medial
rather than lateral sites. The observed diVerences in N400
Table 3
Experiment 1 topographic distribution results for the slow-wave averages at each of the 4 regions in which Context and Electrode Site interacted
Proverb region
4th word
C£A
C£L
C£H
C£A£L
C£A£H
C£L£H
C£A£L£H
¤
¤¤
p < .05.
p 6 .01.
5th word
¤¤
F(3,54) D 7.12
F<1
F<1
F<1
F<1
F<1
F < 1.16
6th word
¤¤
F(3,54) D 5.68
F<1
F<1
F < 1.60
F<1
F<1
F < 1.12
F(3,54) D 5.62
F<1
F<1
F<1
F<1
F<1
F<1
7th word
¤¤
F(3,54) D 4.33¤
F<1
F < 1.13
F < 1.67
F<1
F<1
F<1
44
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
+5.0
A
B
+4.4
Frontal (FZ)
Figurative Context (300–500 ms)
+3.8
-5.0
-2.5
+3.1
0.0
µV
+2.5
2.5
5.0
+1.9
7.5
10.0
-100.0
+1.3
150.0
400.0
650.0
900.0
+0.6
ms
0
Central/Parietal (CPZ)
Literal Context (300–500 ms)
-0.6
-5.0
-1.3
-2.5
0.0
µV
-1.9
2.5
5.0
-2.5
7.5
-3.1
10.0
-100.0
150.0
400.0
650.0
900.0
-3.8
ms
-4.4
-5.0
Fig. 4. (A) Experiment 1 single word grand averages at one frontal site (FZ) and one central/parietal site (CPZ) located on the midline for the third word
of the proverbs. The Wgurative condition is shown in blue and the literal condition is shown in red. (B) The topographical distribution of the mean amplitudes for all electrode locations in the N400 region (300–500 ms) at the third word for both contexts.
between medial and lateral locations is frequently found
(e.g., Federmeier & Kutas, 1999), and are consistent with
research involving intracranial electrode recordings that
show that the neurogenerators for the N400 are likely
located in the anterior medial temporal lobes (e.g., McCarthy, Nobre, Bentin, & Spencer, 1995).
3.2.3. Late positivity analysis (700–1000 ms)
The results of the LPC analysis for all electrode sites are
reported in Table 6. As shown in the table, there was a signiWcant main eVect of context at the third word,
F(1,18) D 4.90, p < .05. This eVect occurred because the literal condition was more positive than the Wgurative condition. There also was a signiWcant interaction between
context and electrode site at the third word,
F(61,1098) D 8.53, p < .001, and at the fourth word,
F(61,1098) D 2.56, p < .01. The sustained frontal positivity in
the slow-wave potentials for the literal condition is the primary cause of the main eVect of context and the interaction
with electrode site. At posterior locations the LPC pattern
is reversed (especially at the fourth word)—the literal condition is less positive than the Wgurative condition. The distribution analysis reported below provides statistical
evidence for these claims. No other main eVects or interactions were found at any of the other words in the proverbs.
Table 5
Experiment 1 N400 and LPC topographic distribution results at each of
the 4 regions in which context and electrode site interacted
C£A
C£L
C£H
C£A£L
C£A£H
CxLxH
CxAxLxH
a
¤
¤¤
3rd word (N400)
3rd word (LPC)
4th word (LPC)
F(3,54) D 3.56a
F(1,18) D 4.51¤
F(1,18) D 2.14
F(3,54) D 6.06¤¤
F<1
F<1
F < 1.88
F(3,54) D 13.54¤¤
F(1,18) D 2.69
F(1,18) D 2.43
F(3,54) D 5.18¤¤
F < 1.51
F<1
F<1
F(3,54) D 2.69
F<1
F<1
F < 1.39
F<1
F<1
F(3,54) D 2.41a
D p > .05 < 10.
p < .05.
p 6 .01.
3.2.4. Late positivity distribution analysis
The results of the topographic distribution analysis for
the third and fourth words are presented in Table 5. At the
third word, context and anteriority interacted,
F(3,54) D 13.54, p < .001. This interaction occurred because
the literal condition was much more positive than the Wgurative condition at prefrontal (mean diVerence D 2.71 V;
F(1,18) D 33.05, p < .001) and frontal sites (mean
diVerence D 2.65 V; F(1,18) D 31.57, p < .001), whereas
these diVerences were much smaller and in the opposite
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
Table 6
Experiment 1 grand average late positivity results (700–1000 ms) for each
of the 7 words in the proverbs
Word
1st
2nd
3rd
4th
5th
6th
7th
¤
¤¤
Context
Electrode £ Context
F<1
F(1,18) D 2.22
F(1,18) D 4.90¤
F<1
F < 1.45
F<1
F < 1.80
F<1
F<1
F(61,1098) D 8.53¤¤
F(61,1098) D 2.56¤
F<1
F < 1.28
F < 1.14
p < .05.
p < .01.
direction at parietal (mean diVerence D .35 V; F < 1) and
occipital sites (mean diVerence D .30 V; F < 1). No other
interactions reached signiWcance.
Both the single-word and the slow-wave analyses
reported above demonstrate that people had less diYculty
integrating the proverbs when they are embedded in literal
than in Wgurative contexts. Both types of averages converge
to show that these diVerences began to occur by the third
word of the proverbs and, in the slow-wave averages, these
diVerences were sustained over the remaining words of the
proverbs.
The slow-wave results also demonstrated that the largest
diVerences were found at prefrontal and frontal electrode
sites, a Wnding that is consistent with previous research
examining the relationship between slow-cortical waves in
sentence processing and working memory load (e.g., King
& Kutas, 1995; Münte et al., 1998). We take the slow-wave
results as compelling evidence that people had less diYculty
integrating the familiar proverbial statements when they
were placed in literal rather than Wgurative-biasing contexts.
The N400 and LPC Wndings in the single-word averages
for the third and fourth word are more diYcult to interpret
as a result of the large diVerences in slow-wave amplitudes
at anterior electrode locations. For example, the distribution analysis for the N400 analysis demonstrated a two-way
interaction between anteriority and context whereby the literal context was much less negative than the Wgurative contexts at anterior positions than at posterior locations. These
diVerences are due to amplitudes at anterior locations capturing both the greater slow-wave positivity for the literal
contexts and the less negative N400 in the literal contexts.
Thus, it could be the case that our N400 results (and LPC
results) are primarily driven by the slow-wave diVerences
rather than diVerences in the N400 and LPC components.
In order to establish whether our N400 and LPC eVects at
the third word are signiWcant at posterior locations (where
they typically are maximal) without the inXuence of the
slow-wave diVerences at anterior locations, we conducted
separate N400 and LPC analysis with all electrode locations anterior to the central electrodes removed from the
analysis. We also conducted the same analysis for the LPC
region at the fourth word.
45
The results of the N400 analysis without anterior electrodes at the third word revealed a robust main eVect of
context, F(1,18) D 13.52, p < .01. As expected, the N400 for
the literal condition (M D .16 V) was less negative than for
the Wgurative condition (M D 1.67 V). However, the main
eVect of context for the LPC region at the third word
(F < 1) and fourth word (F(1,18) D 2.70, p D .12) did not
reach signiWcance. Therefore, our results suggest that our
N400 eVects at the third word are genuine, whereas our
LPC eVects at the third and fourth word are primarily
driven by the diVerences in the slow-wave amplitudes at
anterior electrode locations.
Our N400 results are consistent with previous Wgurative
language research showing that people have less diYculty
integrating the Wnal word of statements when they are
intended to be taken as literal statements rather than as
metaphoric or sarcastic statements (e.g., Coulson & Van
Petten, 2002; Katz et al., 2004; Pynte et al., 1996). Interestingly, the N400 diVerences found between the two contexts
were localized to the third word. This pattern is diVerent
than the slow-wave analysis that indicated people had less
diYculty integrating the familiar statements in the literal
contexts from the third word through to the seventh word.
These diVerences between single word and slow-wave averages should be interpreted with caution, however, as the
100 ms pre-stimulus baselines for the single word averages
following the third word may be inXuenced by N400 eVects
resulting from each preceding word. For example, because
the SOA for each word was 500 ms, the pre-stimulus baseline for the fourth word will fall within the typical N400
range (i.e., 400–500). As a result, the amplitudes of the wave
forms for the subsequent word will be increased or
decreased to the degree that they are away from the baseline value in the 400–500 ms following the onset of the preceding word. The multiword averages reported above can
be useful in this regard because they were conducted with a
baseline that started 200 ms before the onset of the Wrst
word of the proverb. As shown in Fig. 2, there is some evidence, albeit indirect, that N400 amplitudes are less negative in literal than Wgurative contexts at most of the other
words in the proverbs, including the second, fourth, Wfth,
and seventh word. These diVerences in N400 amplitude,
however, are much smaller than that found at the third
word.
Although there was some evidence of a less positive LPC
for the literal than Wgurative contexts at the fourth word,
the diVerence between the two conditions was not signiWcant when only the central and posterior electrode locations where examined. Thus, the LPC data are similar to
previous research (e.g., Coulson & Van Petten, 2002) as
there was less positivity associated with the literal condition
than the Wgurative condition at scalp locations in which the
LPC is typically maximal, although in our case these diVerences did not reach signiWcance.
The question remains, however, about why the diVerences between contextual conditions in the slow-cortical
waves begin to be signiWcant at the third word and,
46
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
similarly, why the largest diVerences in the N400 amplitude
are found at third word. We believe that it is at this point
that people have received enough of the familiar proverbial
statements to recognize them as common Wgurative expressions. As a result, it is at this point that people can begin to
integrate the well-known meanings of these phrases with
the discourse contexts and, therefore, we begin to see diVerences in the ease in which people can integrate the meanings
of the proverbs in the literal and Wgurative contexts. This
claim is consistent with previous self-paced reading results
by Katz and Ferretti (2001) that show by the second word
of the proverbs people began to diVerentiate between familiar and unfamiliar proverbs, and this was true for both the
literal and Wgurative contexts. However, it is important to
note that an additional baseline condition would be
required to ensure that the recognition of familiar proverbs
employed here occurs at the same point in the proverbs.
In summary, the slow-wave averages and the single word
averages clearly show that integrating familiar proverbs
into literal discourse contexts is less diYcult than when they
are placed in Wgurative discourse contexts. However, these
Wndings are not consistent with previous self-paced reading
experiments that have shown that people read familiar
proverbs at the same rate whether presented in Wgurative or
literal biasing contexts (Katz & Ferretti, 2001, 2003). The
self-paced reading data with proverbs are consistent with a
large body of evidence for other instances of highly familiar
forms of non-literal language and, as such, the Wndings of
Experiment 1, based on an arguably more sensitive measure
of temporal processing, have important theoretical implications. Because a diVerent set of passages were employed in
the present study than in the earlier self-pace reading studies, it is diYcult to directly compare the present results with
the earlier null eVect. For example, it could simply be the
case that a self-paced reading study involving the current
item set would produce reading times that are more consistent with the present ERP results. Consequently, Experiment 2 addresses whether the pattern observed here with
ERP data would be replicated in a self-paced reading task
when the same set of items are employed.
4. Experiment 2
Experiment 2 was designed to examine people’s
moment-by-moment comprehension of familiar proverbs
when they are presented in contexts that are either biased
toward their literal or Wgurative meanings. The reading
experiment is a replication and extension of Katz and Ferretti (2001, 2003). The main diVerence here is that we only
investigate familiar proverbs and we examine proverbs that
all have the same length. Using proverbs that are all the
same length permits a Wner-grained analysis of word-byword processing than was employed in the previous experiments, in which the variable number of words in the middle
region of the proverbs were averaged together as a single
region. A second important diVerence is that we employ
almost three times the number of items (i.e., 32 vs. 12), thus
providing an increased representative dataset and thus a
greater likelihood of detecting reading time diVerences if
they exist.
Based on the results of previous studies examining the
inXuence of literal and Wgurative contexts on Wgurative language comprehension (Gibbs et al., 1997; HoVman & Kemper, 1987; InhoV, Lima, & Carroll, 1984; Katz & Ferretti,
2001, 2003), it is expected that overall reading latencies for
proverbs placed in literal and Wgurative biasing contexts
should be similar across each of the critical regions examined. However, if the lack of a diVerence between the two
contextual conditions found in previous research is due to
small item sets and problems associated with averaging
reading times in the mid-region of the proverbs, then we
may Wnd, as we did with the ERP data in Experiment 1,
some advantage in reading times for proverbs in the literal
biasing contexts due to the greater conceptual overlap
between the context and the proverbs than would be found
between the proverbs and the words in the corresponding
Wgurative biasing contexts.
5. Method
5.1. Participants
Twenty-four participants participated in the reading
experiment. All participants were native English speaking
undergraduate students from Wilfrid Laurier University
who received course credit for their participation.
5.2. Materials and procedure
The materials were identical to Experiment 1.
5.2.1. Self-paced reading task
The paragraphs were displayed on a 17 in. Apple monitor controlled by a Macintosh G4. They were presented
using PsyScope (Cohen, MacWhinney, Flatt, & Provost,
1993) in a one-word-at-a-time moving window format.
Paragraphs were initially presented on the screen with each
non-space character replaced by a dash. Participants
pressed a button to reveal the Wrst word of the paragraph.
Each subsequent button press revealed the next word and
replaced the previous word with dashes. Participants read
each paragraph in this manner and then answered a yes–no
comprehension question.
Testing sessions began with 4 practice items. Participants
then read the remaining 128 experimental trials. Each session lasted approximately 1 h. Reading latencies for each
word were recorded by the computer and were measured as
the time interval between successive button presses.
5.3. Design
The analysis was conducted on 10 diVerent regions in
and around the proverbs; the word immediately preceding
the proverbs, each of the seven words comprising the
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
proverbs, and the two words immediately following the
proverbs. The analysis for the two Wnal regions was a gauge
of sentence “wrap-up” eVects.
We conducted 2-way analysis of variance on each
region. The main factor of interest was Context (literal vs.
Wgurative), which was within participants (F1) and within
items (F2). List (F1) and Item Rotation Group (F2) were
used as a between factor to stabilize any variance caused by
rotating participants and items across the diVerent lists
(Pollatsek & Well, 1995). Any reading latency that was
greater than three standard deviations from the mean was
removed from the analysis. Items in which the participants
incorrectly answered the comprehension question were
removed from the analysis.
6. Results and discussion
The mean reading times for each of the 10 critical
regions are shown in Fig. 5. As can be seen, participants
read each word in the proverbial statements at a similar
rate, regardless of contextual bias. Moreover, there was no
evidence of any diVerences in sentence wrap-up eVects at
the two regions following the proverbs. In all regions, the
diVerence in reading times was not signiWcant, all F’s < 1.3.
The results are consistent with previous research by Katz
and Ferretti (2001, 2003) showing that people read familiar
proverbs at the same rate when they are embedded in literal
and Wgurative biasing contexts. These results are also consistent with an extensive body of evidence that show that
people do not need additional time to read other forms of
Wgurative language, such as metaphors, idioms, and indirect
speech acts, compared to their non-literal counterparts (e.g.,
Gibbs, 1989; Gibbs et al., 1997; HoVman & Kemper, 1987;
InhoV et al., 1984). The results of Experiment 2 are inconsistent with all models that obligate the reader to Wrst process the literal sense of a proverb, such as the standard
pragmatic approach of Searle (1979) or a literal-Wrst model
speciWc to proverb processing (Honeck, 1997).
We recognize that it is diYcult to draw conclusions from
experiments that produce a null eVect, but we suggest that
there are a number of reasons why the self-paced moving
400
Figurative Context
375
Literal Context
350
325
300
275
250
Before First Second Third Fourth Fifth
Sixth Seventh After 1 After 2
Proverb Region
Fig. 5. Experiment 2 mean reading times (ms). Error bars with larger caps
capture the literal condition and bars with smaller caps capture the Wgurative condition.
47
window procedure used here would have detected diVerences between reading times had they been present. First, in
our previous research examining the inXuence of literal and
Wgurative contexts on proverb interpretation (e.g., Katz &
Ferretti, 2001) we investigate both familiar and unfamiliar
proverbs. As mentioned above, in that study we also did
not Wnd diVerences in reading times for familiar proverbs
but we did Wnd robust contextual inXuences on reading
times for unfamiliar proverbs. Thus, in that study we replicate the same null eVect seen here but also show that moving window methodology is sensitive to diVerences in how
easily people can construct Wgurative interpretations in the
literal and Wgurative contexts for unfamiliar proverbs.
Moreover, in the present study we used almost three times
the number of items per condition and controlled for the
overall length of the proverbs and still did not Wnd any
reading time diVerences. Second, as mentioned above, the
null eVects observed here are consistent with a large body
of evidence that suggests that people often do not need
more time to read Wgurative statements in Wgurative than
literal contexts. Third, other researchers have shown that
moving window methodology is sensitive to the earliest
moments of processing in other domains of language comprehension, such as when examining the interaction
between syntax and semantics during syntactic ambiguity
resolution (e.g., McRae, Spivey-Knowlton, & Tanenhaus,
1998). Fourth, examination of Fig. 5 and our statistical
analysis show that there were no diVerences in reading
times that were even close to being signiWcant. In short, we
believe that our present experiment would have been sensitive to reading times had they been present.
A diVerent, but related issue, is how the diVerent presentation rates for each word across the two experiments may
have led to the diVerences observed between the experiments. Although words were presented one at a time in
both experiments, in Experiment 1 the words were presented for a 300 ms duration with an SOA of 500 ms (note
that this is a standard SOA used in ERP investigations of
language comprehension), whereas in Experiment 2 people
were able to read each word at their own rate. It is interesting to note that people in Experiment 2 read each word for
approximately 325 ms on average, only slightly slower than
the 300 ms word presentation duration in Experiment 1.
However, given the SOA of 500 ms in Experiment 1, this
suggests that people were forced to read at a rate of 175 ms
per word slower on average in Experiment 1 than Experiment 2 (keep in mind that we comparing two diVerent
groups of people). In our opinion, it is diYcult to see how
slowing people down while they read by such a small
amount of time would make it harder rather than easier to
integrate the exact same phrases in Wgurative contexts than
for literal contexts. For example, given that the phrases
were familiar statements we would expect, as suggested
above, that people would probably retrieve the meaning of
the phrases long before they Wnished reading those phrases.
Presumably giving people more time to retrieve the meaning of those familiar phrases by slowing down presentation
48
T.R. Ferretti et al. / Brain and Language 101 (2007) 38–49
rates would give them more time to integrate the meaning
of those familiar statements with the preceding discourse
contexts. Thus, it is diYcult to see how the slight diVerences
in word presentation rate across the two experiments would
lead to more diYculty in the Wgurative than literal condition in Experiment 1, but not lead to any diVerences in
Experiment 2.
7. General discussion
The present research extends previous research on Wgurative language processing in a number of ways. Perhaps
the most intriguing Wnding is that our ERP results show
that people have less diYculty when processing familiar
proverbial phrases placed in contexts that invite a literal
interpretation than when placed in Wguratively biasing contexts, whereas no such diVerences were found for the same
items in a self-paced reading task. In our case, we directly
compared self-paced reading times and ERP potentials to
identical stimulus sets and found clear diVerences in the
pattern of results across the two measures. The diVerences
between the two methodologies speak to the importance of
using converging measures to investigate Wgurative language processing. In particular, our results add to a small
but growing body of literature that shows how ERP methodology provides a measure that is more sensitive than
reading time measures in indexing the diYculty readers
have when comprehending Wgurative statements embedded
in diVerent contexts (e.g., Coulson & Van Petten, 2002;
Katz et al., 2004).
In the present case, we examined slow-wave potentials
that are known to be sensitive to working memory load
during sentence processing and also N400 and LPC amplitudes. As such, the diVerences in ERP amplitudes we
observe here between the literal and Wgurative-inviting contexts is consistent with the interpretation that the diVerences reXect a greater ease in integrating the proverb with
the discourse context when it is being used in its literal sense
than in its familiar non-literal sense, an interpretation also
consistent with that given by Coulson and Van Petten
(2002) in their ERP study of metaphor processing. Moreover, here we Wnd that this diVerence emerges by the third
word of the proverb. Thus problems in integrating the proverbial sense of the sentence into the emerging discourse
structure is found well before the reading of the proverb
has been completed. Recall that the proverbs we employed
were familiar and, therefore, the non-literal, proverbial
sense should have been highly salient (see Giora, 2003).
Consequently, problems in integration found with the Wgurative context are not likely to be due to a problem in
accessing a viable non-literal meaning of the proverb per se,
but to diYculty in creating coherent discourse. We argue
here that this diVerence is due to the characteristic of proverbs that, when used literally, they tend to be true both literally and Wguratively. Thus a proverb used literally shares
greater conceptual overlap with the context than when the
same statement is preceded by non-literal context.
7.1. Implications for models of Wgurative language processing
Our results are most consistent with models that posit
that people construct a Wgurative interpretation very early
in the processing of a Wgurative statement when the contexts are suYciently constraining (Gibbs, 1994; Gibbs et al.,
1997; Katz & Ferretti, 2001). The fact that we Wnd diVerences in slow-wave potentials for the two contexts at the
third word of the proverb is strong evidence against models
of Wgurative language processing which posit that the literal
meaning of an entire statement must be processed prior to
constructing a Wgurative meaning (e.g., Grice, 1975).
The Wndings also appear problematic for another theory
that assumes obligatory access of sentence meaning,
namely, the graded salience hypothesis (Giora, 2003). Proponents of this approach would need to explain why the
familiar (and hence salient) proverbs used in the ERP
experiment were more diYcult to integrate into the Wgurative context than into the literal context, because that theory proposes that it should be at least as easy, and maybe
even easier, to integrate into the Wgurative context than into
the literal context. Taken together, our data is consistent
with models that assume we actively construct interpretations during discourse processing, rather than retrieve
entrenched meanings from semantic memory.
In conclusion, our results indicate the utility of using
ERP methodology to investigate slow-wave potentials that
develop over sentences and clauses for the on-line investigation of Wgurative language processing. The present
research is the Wrst to show that people have less diYculty
integrating familiar proverbs presented in literal contexts
than Wgurative contexts, data consistent with theories that
emphasize the active construction of meaning (literal and
non-literal alike) during discourse processing.
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