Top Lang Disorders
Vol. 33, No. 2, pp. 152–164
c 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright Verb Selection and Past-Tense
Morphology
Crystal’s Criteria Revisited
Brian Weiler
Research findings concerning verb-level influences on past-tense morphology carry implications
for the careful selection of treatment targets. Using 6 of the broad criteria for “good verbs to
choose” proposed by D. Crystal (1985) more than 25 years ago as a framework, this article
summarizes some of the more recent research with a nod toward potential clinical applications.
Specific semantic, frequency, developmental, phonological, and syntactic considerations for verb
selection are discussed. Information is provided with respect to typical language learners and,
when possible, children with language impairment. The article concludes with thoughts on using
research findings to inform a guided approach to the selection of past-tense intervention targets.
Keywords: David Crystal, intervention targets, lexical aspect, past-tense morphology, SLI, verb
frequency, verb phonology, verb selection
D
IFFICULTY with the past-tense marking
of verbs beyond the typical time period
during which children optionally mark tense
is a defining clinical marker of children with
primary language impairment (Rice, Tomblin,
Hoffman, Richman, & Marquis, 2004; Rice &
Wexler, 1996). Eventual proficiency with this
structure in oral language may belie a persistent underlying linguistic vulnerability, as
evidenced by omissions of past-tense markers in the written language output of children
Author Affiliation: Department of Hearing and
Speech Sciences, Vanderbilt University Medical
Center, Nashville, Tennessee.
Preparation of the manuscript was supported
by a Preparation of Leadership Personnel grant
(H325D080075; PI: Schuele), U.S. Department of Education. The content is solely the responsibility of the
author and does not necessarily reflect the official views
of the supporting institutions, agencies, or foundations.
The author has disclosed that he has no significant relationships with, or financial interest in, any commercial
companies pertaining to this article.
Corresponding Author: Brian Weiler, MS, Department of Hearing and Speech Sciences, Vanderbilt
University Medical Center, 1215 21st Ave South,
Medical Center East 8310, Nashville, TN 37232
([email protected]).
DOI: 10.1097/TLD.0b013e31828f50b8
with language impairment (Windsor, Scott, &
Street, 2000). Accordingly, specific instruction of past-tense morphology is a common
sight on many treatment plans.
It behooves language interventionists to differentiate morphological instruction of the
past tense in a way that maximizes acquisition of the target structure. Such differentiation is commonly approached with a consideration of the elicitation or production task.
Tasks may span elicited imitation (e.g., repeat
what I say) to open-ended questions (e.g.,
What did the boy do?) depending on the individual strengths and needs of a child at a given
point in his or her language development.
What is less likely considered during the
planning of past-tense interventions is the
choice of which verbs to teach. More than
25 years ago, David Crystal (1985) wrote,
“The question of deciding which verbs to
teach first, in a language-teaching program,
is too important to be left to chance” (p. 48).
My concern is that, despite a quarter century
of research literature to draw from, this decision is still largely based on convenience,
if not chance. Verb targets quickly become
arbitrary when, for example, picture stimulus cards or play routine manipulatives are
chosen without consideration of the specific
152
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Verb Selection
lexical factors known to impact the likelihood
of tense marking. Certain morphological curricula do offer some guidance. Notably, the
regular past-tense targets in the methods and
materials for Teaching Morphology Developmentally (Shipley & Banis, 1989) are explicitly classified by the allomorphs /-t, -d, -əd/.
Other clinical materials, such as Months of
Morphemes (Haskill, Tyler, & Tolbert, 2001),
offer lesson plans with thematically appropriate verbs (e.g., cooking actions) without
further discussion of expectations relative to
past-tense marking difficulty specific to the
target verb. For the most part, it appears that
clinicians are left to their own devices with
regard to verb target selection. Whereas selection according to a thematic content unit
(e.g., seasonal vocabulary or the zoo) may
be appealing to both child and the clinician,
there is sufficient evidence to glean from the
research literature to suggest that verb stimulus selection should be more judicious and
intentional.
Despite the scarcity of studies of evidencebased practices related to verb target selection in morphological interventions, the
research literature does offer findings that support evidence-based principles of language intervention. These principles can be broadly
aligned with the essential criteria for careful
verb selection established by Crystal (1985).
Because of the centrality of verbs to sentence structure development, efforts should
be made, according to Crystal, to minimize
failure lest children be “put off by verbs,”
which, in turn, could slow language development. Therefore, his criteria for verb selection
reflect what could generally be considered to
be the most facilitative for learning. The original criteria were divided into two categories:
Functional and Formal. The Functional criteria relate to the contexts within which the
verbs are used (i.e., their functions), whereas
the Formal criteria reflect the structural characteristics (pronunciation, grammar, meaning) of the verbs themselves (i.e., their forms).
The purpose of this article was to expand
the current evidentiary basis of six of Crystal’s
criteria for verb selection with a clinically use-
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ful summary of relevant research findings related to past-tense marking from the interim
period—four functional and two formal. The
more informed clinicians are about some of
the verb-level factors known to facilitate pasttense marking, the more likely they are to use
information from empirical evidence to guide
their clinical decisions.
FUNCTIONAL CRITERIA
Criterion 1
The verbs should express a clear physical, dynamic action (such as jump, kick, drink) and not
be abstract, static, vague or mental (such as know,
do, have, feel, change). It should be noted that
these dynamic verbs can be classified into several
types—most importantly, into whether the action
has a clear beginning-point (open, knock), a clear
end-point (kick, fall down), or has no clear-cut
boundaries (play, run). (Crystal, 1985, p. 49)
The first of Crystal’s criteria for verb selection can be revisited in light of more
recent research into lexical aspect considerations of children’s past-tense productions. Aspect, generally speaking, refers to “the way
the grammar marks the duration or type
of temporal activity denoted by the verb”
(Crystal, 2008, p. 38). In English, an aspectual distinction is made, for example, between
progressive (e.g., I was sleeping) and nonprogressive (e.g., I slept). Lexical aspect relates to
the inherent semantic and temporal properties of situations described by individual verbs
and their adjuncts (Li & Shirai, 2000). Adjuncts
are the “optional or secondary element(s) in
a construction” such as adverbs and modifiers (Crystal, 2008, p. 12). According to Smith
(1997), the presence or absence of the state,
durative, and telic properties determines classification among the four lexical aspect categories, which had been established earlier
by Vendler (1967): state, activity, accomplishment, achievement. These relationships are
illustrated in Table 1.
The primary distinction between the lexical
aspect categories of activity and accomplishment concerns the telic property. Telicity distinguishes verbs that can be characterized as
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TOPICS IN LANGUAGE DISORDERS/APRIL–JUNE 2013
Table 1. Lexical aspect categories
Category
State
Activity
Accomplishment
Achievement
Properties
[+
[+
[+
[−
durative] [ −
durative] [ +
durative] [ +
durative] [ +
Example
dynamic] [ −
dynamic] [ −
dynamic] [ +
dynamic] [ +
telic]
telic]
telic]
telic]
I wanted it.
She rode the horse.
He tied his shoes.
She blew out the candle.
Note. [ + durative] = event takes time to occur; [ − durative] = event occurs instantaneously. [ + dynamic] = event
involves motion; [ − dynamic] = event is a state. [ + telic] = event has a defined endpoint; [ − telic] = event has an
undefined endpoint. From “Interaction of Lexical and Grammatical Aspect in Toddlers’ Language,” by B.W. Johnson and
M. E. Fey, 2006, Journal of Child Language, 33, pp. 419–435, which drew on the work of The Parameter of Aspect
(2nd ed.), by C. S. Smith, 1997, Dordrecht: Kluwer Academic Publishers. Adapted with permission of the publisher.
having an endpoint from those that have no
specified endpoint. For example, the phrase,
walk to the park, suggests an endpoint and
would be characterized as an accomplishment
with the temporal feature of being telic ( +
telic). Conversely, the phrase, stroll in the
park, does not suggest an endpoint and would
be characterized as an activity with the temporal feature of being atelic ( − telic). Drawing
on the lexical aspect categorical framework
initiated by Vendler (1967) and refined by
Smith (1997), Johnson and Fey (2006) examined young children’s use of past-tense morphology in reference to events that were either bounded by an inherent endpoint (e.g.,
She pushed a train onto a box) or unbounded
by an inherent endpoint (e.g., She pushed a
train in circles). They found that typically
developing 2-year-olds imitated past-tense
morphology with higher accuracy for verb
contexts bounded by an endpoint (i.e., accomplishments) than unbounded by an endpoint (i.e., activities) (effect size: d = .36). The
experimental task was replicated with similar
results in a case study with a 4-year-old with
specific language impairment (SLI; Johnson &
Morris, 2007).
Additional investigations into the potential
interaction between lexical aspect and grammatical tense marking have addressed the telic
and durative properties. The term “durative,”
within a consideration of aspect, refers to “an
event involving a period of time” (Crystal,
2008, p. 159). The aspectual distinction be-
tween achievements and activities relates to
both telicity and duration. Whereas achievements are bounded by an endpoint and instantaneous (e.g., He popped the balloon),
activities are unbounded and gradually occurring (e.g., He rode his bike). Leonard, Deevy,
et al. (2007) found that, in an elicitation probe,
3-year-olds with typical language mark regular
past tense with greater accuracy for achievements than activities (d = .72). The facilitative advantage of achievements over activities
observed in children with typical language
skills in the study was not seen, however, in
5-year-old children with language impairment
(d = .15).
To specifically address whether the duration involved in reaching an event’s endpoint
influences past-tense marking, Weiler and
Schuele (2011) compared responses from typically developing children to a past-tense elicitation prompt across telic verbs that differed
on the durative property (i.e., achievements
vs. accomplishments). Comparable overall accuracy in past-tense marking was found across
the two lexical aspect categories under investigation, χ 2 (1) = .156, p > .50. Considering
this finding alongside the aforementioned investigations of lexical aspect and past-tense
marking, it appears that typical preschoolers are better able to exploit their past-tense
morphology skills with verbs that describe an
event with a specified endpoint but are relatively uninfluenced by whether that endpoint
was reached instantaneously or gradually.
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Verb Selection
Although current findings for children with
language impairment are mixed and limited,
clinicians can still apply evidence from typical development to inform past-tense interventions. Specifically, Crystal’s initial criterion
that verbs taught early in the development of
a language structure should express “a clear
physical, dynamic action” can be refined to
favor those verbs and/or verb phrases that
represent a completed action with a defined
endpoint. The application of this evidencebased principle might extend to the selection of past-tense elicitation stimuli such as
“This boy is riding his bike to school. What
did he do?” over similar stimuli that are unbounded by an endpoint such as “This boy
is riding his bike. What did he do?” Research findings indicate that the first stimulus
may be more prototypical and salient, from
a child’s perspective, of a completed event
and therefore more likely to elicit accurately
a response marked for past tense. Picture
prompts may not fully capture the “verbness”
of such an event because of their visually static
and two-dimensional presentation (Klimacka
& Brunger, 1999). Instead, presenting short,
and preferably wordless, video clips or using
toy manipulatives to “act out” the event may
more realistically convey the completion of an
action. Given the unique challenges children
with language impairment have in acquiring
past-tense morphology, clinicians should consider stimuli that most clearly convey the conclusion of an event or situation. Doing so will
help ensure that the grammatical aspect of
past perfective tense is made explicit to the
child.
Criterion 2
The verbs should be familiar to [the child].
(Crystal, 1985, p. 49)
The frequency with which children use
verbs inflected for past tense provides a window into their relative familiarity with those
verbs. In other words, clinicians can be reasonably confident that more frequently produced verbs should, by extension, be more
familiar to children.
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Verb frequency also appears to influence
regular past-tense marking. In a study of pasttense marking in children with and without
SLI, Oetting and Horohov (1997) identified
frequently and infrequently occurring verbs
inflected for past tense from a child corpus
of spontaneous speech (Hall, Nagy, & Linn,
1984). The results of their productivity probe
showed that children with SLI as well as normally developing, mean length of utterance
(MLU)-matched peers were significantly more
likely to mark past tense on frequently occurring (vs. infrequently occurring) inflected
verbs requiring the allomorphs /-d/ or /-t/
whose bare stems end in nasal, stop, and
fricative consonants (e.g., climb, hug, jump,
cough; ds (SLI) = .84 [/-d/], .86 [/-t/]; ds
(MLU-matched) = .73 [/-d/], .48 [/-t/]). The
difference in past-tense marking according to
child frequency value was not observed for
those verbs whose bare stems end in liquids,
glides, or vowels and require the /-d/ allomorph (e.g., pour, smell, cry), d (SLI) = .46;
d (MLU-matched) = − .59.
When instructing regular past-tense morphology, at least for verb stems ending in
consonants, a consideration of the verb’s inflected frequency across child language samples appears merited. Frequently occurring
targets are apt to be more familiar and
salient to the child, thereby allowing for
greater focus on the morphological rule for
past tense instead of teaching verb meaning. Language interventionists can access agespecific, child-inflected verb frequency values
culled from more than 5,000 English transcriptions from the CHILDES (Child Language
Data Exchange System) database available at
http://childfreq.sumsar.net/ (Bååth, 2010).
In addition to frequency counts derived
from child corpora, verb familiarity can also
be considered relative to the individual child’s
experiences. There is inherent variability in
children’s familiarity with verbs, depending
on the individual child’s home and school environments and routines. To maximize the
familiarity of verb targets for a grammatical intervention such as past-tense morphology, clinicians are advised to solicit input
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TOPICS IN LANGUAGE DISORDERS/APRIL–JUNE 2013
from parents and teachers whenever possible. Interviews to inquire about familiar routines, termed routines-based interviews (RBI;
McWilliam, Casey, & Sims, 2009), are one
vehicle of gathering information about the
types verbs apt to be familiar to a child. The
RBI is a semistructured interview comprising questions about the child’s daily routines,
from the beginning to the end of a typical
day. McWilliam et al. (2009) noted that “the
stress on routines is because of the behavioralecological notion that routines are the context in which the need for intervention is ‘authentically’ determined” (p. 225). The family responses to the RBI can then be used
to plan interventions. An application of the
RBI approach to a morphological intervention targeting past tense may thus extend to
the selection of “authentic” or “ecologically
valid” verbs familiar to the child. For example, if a mother reported that a routine conversational topic with her child related to the
child’s involvement with swimming lessons,
then verbs such as float, dive, dip, and dunk
might emerge as logical candidates for intervention targets.
Criterion 3
The verbs should be easy to learn, in the sense
that they are among the earliest verbs to appear in
the normal language acquisition process. (Crystal,
1985, p. 50)
The classic observational studies of Bloom
(1991) have provided valuable insight into
the acquisition of verbs across categories of
verb relations. Bloom’s study of four toddlers
ranging in age from 18 to 25 months indicated, for example, that action verbs (e.g.,
Open de buttons) appear before state verbs
(e.g., I hear childrens). Beyond such categorical information, however, knowledge of children’s acquisition of specific verbs in their
expressive lexicon has emerged more recently. In particular, a normative study for
The McArthur-Bates Communicative Development Inventories: Words and Sentences (CDI;
Fenson et al., 2007) yielded the proportion
of children at each month between 16 and
30 months of age whose parents reported
productive use of 102 early-emerging verbs,
or “action words” listed on the form. Responses from more than 1,000 parents were
compiled in a public, Web-based database,
available at http://www.sci.sdsu.edu/lexical
(Dale & Fenson, 1996). By the age of
30 months, the vast majority of verbs (97 of
102) were reportedly produced by at least half
of the children. In addition, a majority of the
verbs listed on the inventory (71) were reportedly produced by at least 80% of 30-montholds.
As a result of these findings, specific verblevel information available from the CDI lexical development norms can be more systematically applied to the selection of treatment
targets relative to their emergence in the expressive lexicon. For example, whereas a clinician might intuit that a verb such as skate is
early emerging, results from the CDI database
suggest that less than half of all 30-montholds have produced this word. Certainly, a
30-month-old would not be a likely candidate
for past-tense intervention. Instead, the point
is that, for children for whom morphological
interventions are appropriate, verbs that have
been a part of their productive lexicon for a
longer period of time may be more amenable
to treatment. Such verbs and their meanings
are likely to be more deeply ingrained in the
child’s linguistic repertoire. Therefore, the
child’s cognitive and linguistic resources can
potentially be allocated more to the learning
of past-tense morphology and less to the learning of new verbs.
Like Bloom’s (1991) seminal early work,
Brown’s (1973) observational studies offer
valuable insight into the normal language acquisition process. Considering more recent
studies alongside Brown’s findings can build
on the foundation he established. For example, Brown listed irregular past-tense verbs as
developing fifth sequentially among the 14
grammatical morphemes he analyzed. Irregular past-tense forms thus are expected to
appear before regular past-tense forms (listed
ninth) in Brown’s account of morphological
development. As discussed later, however,
the use of Brown’s sequence as the sole basis
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Verb Selection
for intervention goals, particularly for mastery
(not just marking) of irregular past-tense morphology, invites concern. Although certain irregular past-tense verbs appear frequently in
the language of children by 3 years of age, it is
commonly thought that early-occurring forms
such as ate and broke are learned by rote as
whole, unanalyzed units. Shortly thereafter
in development, as children begin actively
to deploy regular past-tense rules, overregularizations such as eated and broked appear
(Marcus et al., 1992). This U-shaped developmental pattern of early accuracy, followed
by subsequent inaccuracy, is completed only
later in language development when children
relax an overreliance on the regular past rule
to produce correct irregular past forms consistently.
What does this have to do with verb selection for past-tense interventions? Most importantly, the developmental timeline within
which children master the irregular past tense
(i.e., when they cease to overregularize) appears to vary quite significantly according to
the verb. Failure to recognize this clinically
may result in unnecessary training of verbs in
children younger than the age of mastery indicated by normal development. For example,
Kuczaj (1977) found that overregularization
errors on irregular past-tense verbs are produced by children who have already demonstrated stable control of the regular past-tense
rule. Moreover, the acquisition of irregular
past-tense forms can persist until the age of
6 years or beyond (Menyuk, 1963). Indeed,
using 80% accuracy in a sentence completion as criterion, Shipley, Maddox, and Driver
(1991) found that among typical language
learners, many irregular past-tense forms were
not “mastered” until 6, 7, or 8 years of age.
In fact, several verbs continued to be commonly overregularized through the age of 8;
11 years. Irregular verbs most prone to a delay
in the shift from being overregularized to being marked accurately according to the adult
language were those that require a final consonant change from /d/ to /t/ (e.g., build, send,
bend; Shipley et al., 1991).
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Heeding Crystal’s (1985) advice to teach
verbs according to the normal acquisition
process, language interventionists are encouraged to reference the ages of irregular pasttense mastery for specific verbs reported
by Shipley et al. (1991) in order to avoid
exhausting valuable teaching time correcting otherwise age-appropriate overregularizations. Concerning the irregular past tense,
Brown’s order of acquisition should serve as
a starting point but not as a roadmap for morphological intervention. Whereas normal developmental sequences may “represent the
easiest or even the necessary order” of acquisition, it is important that clinicians not
“take a description of the course of normal acquisition as a prescription for the way
language must be taught” (de Villiers & de
Villiers, 1978, p. 270).
Criterion 4
The verbs should be frequent in adult language.
(Crystal, 1985, p. 50)
This recommendation for verb target selection has found some empirical backing in the
past-tense experimental literature. Notably,
Marchman, Wulfeck, and Weismer (1999)
examined how the frequency of adult usage of specific verbs inflected for past tense
might impact children’s responses on a pasttense elicitation task. Frequency values for
past-tense forms of verbs were taken from
adult, White, middle-class samples (Hall et al.,
1984) and were divided into low- and highfrequency categories. Results from the elicitation task showed that children with both
typical and impaired language skills were less
likely to mark past tense on low-frequency
regular and irregular verbs. Both groups, but
particularly children with SLI, were more
likely to omit past-tense morphology on those
verbs that were both low in adult lexical
frequency and whose bare stem ended in an
alveolar stop consonant (e.g., build, mend).
Incorporating Crystal’s (1985) evidencebacked advice into clinical practice can be
accomplished through accessing adult lexical
frequency values via the CHILDES Parental
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TOPICS IN LANGUAGE DISORDERS/APRIL–JUNE 2013
Corpus (Li & Shirai, 2000; MacWhinney,
2000). This corpus consists of utterances
produced by parents, caregivers, and experimenters in largely child-directed language
contexts (e.g., dinner table talks, activities of
free plays, and storytelling). Frequency of occurrence values for more than 24,000 words
types from this corpora, including verbs inflected for past tense, can be found at http://
childes.psy.cmu.edu/derived/parentfreq.cdc.
FORMAL CRITERIA
Criterion 5
The verb should have a pronunciation which
presents as few problems as possible. (Crystal,
1985, p. 50)
Whether because of articulatory ease,
phonotactic probability, neighborhood density, or some combination of these or other
factors, the fact that the phonological properties of verbs impact past-tense marking accuracy is well represented in the literature.
Whereas some phonological characteristics
are facilitative, others appear to pose, as Crystal notes, “problems.” Whether or not the nature of such problems rests purely in “pronunciation,” or, more likely, in general linguistic
competence, is beyond the aim of this article.
Instead, the following summarizes some of the
research findings on phonological influences
on past-tense marking.
Recognition of the allomorphic variations
of regular past-tense morphology, /-t, -d, -əd/,
is expected of speech–language pathologists,
particularly those serving children. What may
be less familiar to clinicians are research findings showing that the likelihood of past-tense
marking may not be equally dispersed across
the three allomorphs. Importantly, bare stem
verbs ending in the alveolar stop consonants
/t/ or /d/, and thus taking the syllabic marker
/-əd/ if regular (e.g., paint-ed, land-ed), were
less likely to be marked for past tense in an
elicitation probe than bare stem verbs ending
in a phoneme other than /t/ or /d/ (Marchman,
1997; Marchman et al., 1999). Verb stems
ending in /t/ or /d/ may be problematic for
children because there are bare stem verbs
ending in alveolar stop consonants that are
legitimately zero-marked for past tense (e.g.,
hit, bid, cut). Interestingly, the omissions of
past-tense marking among children with SLI,
when compared with those with normal language, were even more highly predicted by
the stem final phonology of the verb. This
finding was particularly evident among verbs
with low adult-inflected frequency values
(Marchman et al., 1999).
The effect of such an interaction between
more than one verb-specific characteristic
(e.g., stem final phonology and frequency)
on the likelihood of past-tense marking was
also observed by Oetting and Horohov (1997).
Results from an elicitation probe revealed
that children with SLI and younger controls
matched on MLU were significantly more
likely to mark regular past tense on lowfrequency inflected verbs ending in a liquid
or vowel (e.g., pull, tie) than low-frequency
verbs ending in consonants requiring a /d/ or
/t/ allomorph, ds (SLI) = .78 [/d/], .64 [/t/]; ds
(MLU-matched) = 1.40 [/d/], .94 [/t/]. Such a
difference for high-frequency inflected verbs
was not significant. Eyer and Leonard (1994),
in a case study of a past-tense intervention
for a child with SLI, also reported on an apparent advantage for marking past tense on
verbs whose bare stems end in vowels. They
found that the child’s limited use of regular
past-tense inflections and overregularizations
occurred on verbs such as dry and blow.
Another potentially influential variable is
the phonological composition of stem verbs
marked for irregular past tense with respect
to vowel change (e.g., fly → flew). The contrast of the vowel in the verb stem form
and the vowel in the inflected form can be
viewed according to which vowel is dominant
and which is recessive. Dominant vowels may
be considered more phonologically salient in
that they have a specified place of articulation
(e.g., + back, + high, + low, or + round),
are diphthongs (e.g., / /, /ei/), or have high
phoneme frequencies (Stemberger, 1993). In
contrast, recessive vowels are less phonologically salient in that they have an underspecified place of articulation (e.g., − back, − high,
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Verb Selection
− low, or − round), are monothongs (e.g.,
/ /, /ε/), or have low phoneme frequencies.
In some cases, the dominant vowel is contained within the stem verb such as in the
uninflected verb throw. When the verb undergoes a vowel change during past-tense inflection, the vowel may then become recessive,
such as in the verb threw. For other verbs,
the stem vowel is recessive and becomes
dominant only when inflected for past tense
(e.g., come → came). Testing the hypothesis that dominant vowels represent the “optimal phonological form” and should therefore “be more easily produced,” Marchman
(1997, p. 287) found that children were indeed more likely to mark past tense on past
dominant (vs. stem dominant) vowel change
verbs. In other words, past-tense marking was
more likely to occur when the vowel shift reflected a movement of stem recessive (come)
to past dominant (came). Those verbs with
stem dominant vowels that ended in alveolar stop consonants (e.g., bite) were the
most unlikely to be marked for past tense
use.
Neighborhood structure has also been considered with respect to phonological features potentially impacting past-tense marking. Neighborhood structure is determined
by the frequency of co-occurrence of certain
phonological patterns in words (Marchman
et al., 1999). Verbs that belong to the same
neighborhood are those that share the same
final vowel or vowel–consonant phonemes.
When considering past tense, the verbs shake
and take are good neighbors or “friends” in
that their shared bare stem ending holds up in
the past tense (shook, took). On the contrary,
shake and bake are enemies in the past-tense
neighborhood because their inflected forms
do not share final vowel–consonant phonology (shook, baked). It turns out that being
a good neighbor is indeed advantageous, at
least insofar as past-tense marking. Marchman
(1997) found that children with typical language skills were more likely to mark past
tense in an elicitation probe on verbs from
“friendly” neighborhoods (i.e., more shared
co-occurrences between bare stem and past-
159
tense forms) than their performance on verbs
from “unfriendly neighborhoods.”
Finally, the phonotactic probability of pasttense endings appears to influence children’s
command of past-tense morphology. Phonotactic probability relates to the likelihood that
the phonetic content of inflected verbs could
occur in monomorphemic words. For example, the [ld] blend in rolled also can occur in
monomorphemic words such as cold. On the
contrary, the [Nd] blend in hanged does not
occur in single-morpheme English words. Research has shown that children with SLI, but
not younger language ability-matched controls, are less likely to use regular past-tense
endings when the phonetic context does
not appear monomorphemically (d = .70;
Marshall & van der Lely, 2006). Extending
these findings by controlling for previously
learned inflected forms, Leonard, Davis, and
Deevy (2007) used novel verbs referring to
novel actions and found that children with SLI
marked past tense more frequently on verbs
with high (vs. low) stem and inflected phonotactic probabilities (d = .98). This phonotactic
probability effect on past-tense marking was
not observed in the MLU- or age-matched control groups.
Criterion 6
Lastly, there is the question of which syntactic considerations we should take into account.
(Crystal, 1985, p. 50)
If the goal of a grammatical intervention
targeting past-tense morphology production
is to aid children in becoming better language
users, then the grammatical form, in and of
itself, should rarely be the only component
of language targeted (Fey, Long, & Finestack,
2003). In considering verbs to target, Crystal
(1985) noted that “the most important factor
is that verbs should allow an easy transition
to the next stage of syntactic development”
(p. 50). By the elementary school years, typically developing children and, to a lesser extent, children with language impairments use
a variety of complex sentence structures in
spoken language (Marinellie, 2004; Schuele
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TOPICS IN LANGUAGE DISORDERS/APRIL–JUNE 2013
& Dykes, 2005; Tyack & Gottsleben, 1986).
To limit past-tense intervention to simplesentence productions, therefore, would represent a failure to “make use of grammatical constructions in pragmatically felicitous
contexts” (Fey et al., 2003, p. 5). In other
words, clinicians are cautioned against assuming that proficiency with past-tense morphology in simple sentences will extend to more
complex sentence structures without training. On the contrary, evidence suggests that a
potential tradeoff exists between increasingly
complex sentence structures (e.g., finite complement clauses such as John remembered
where Sue hid) and accuracy in past-tense
morphology (Owen, 2010; Owen & Leonard,
2006; Weiler & Schuele, 2012). Consequently,
target selection for past-tense interventions
should be made with consideration of those
verbs that can take a clausal complement.
Complement-taking mental or cognitive-state
verbs such as wonder, know, remember, and
think (e.g., He wondered where Mary would
go) are pragmatically useful target candidates.
One final note related to syntactic considerations in past-tense elicitation procedures
applies to all verbs. Elicited production tasks
and elicited imitation tasks have been offered
as alternatives to spontaneous language samples, particularly when a specific and/or infrequently occurring structure, such as the past
tense, is of interest. In an elicited language
production task, the examiner sets up a context, using verbal and nonverbal prompting,
that creates a condition for the production of
the target structure (Thornton, 1996). Essential to this condition is the prompting for a syntactic frame that obligates the inflected verb
form. The elicitation task must make it likely
that children will attempt the target of interest. An investigation by Barako Arndt, Weiler,
Eisenband, and Schuele (2012) examined the
necessary components in a child’s response
to ensure a valid measure of grammatical performance on the Past Tense probe of the Test
of Early Grammatical Impairment (TEGI; Rice
& Wexler, 2001). They questioned whether
a valid measure of linguistic skill requires
that the child produce the subject of the
clause (interchange b) and not just the verb
phrase and its complements or adjuncts (interchange a).
Examiner–child verbal interchanges
(a) E: Here the girl is planting the flowers.
Now she is done.
E: Tell me what she did.
C: Plant flowers.
(b) E: Can you start with she?
C: She planted flowers.
E: Great story.
The findings of this study indicated that
responses to the Past Tense probe that include only the verb phrase with an unmarked
verb are not consistently construed as obligatory past-tense contexts for preschool children. For the majority (65%) of interchanges,
initial subjectless responses with unmarked
verbs that were reprompted by the examiner
to include a response with a third person subject also included a main verb marked for past
tense. This finding is consistent with a similar
study of third person present tense responses
from the Third Person Singular Probe of the
TEGI (Eisenband, Schuele, & Barako Arndt,
2011). Thus, child responses that include an
unmarked lexical verb without a subject may
provide insufficient information about the
child’s ability to mark tense in obligatory contexts. Rather, the child’s underlying structure
may be an utterance with an imperative or an
elided auxiliary “do” syntactic structure. To
ensure that the syntactic frame obligates pasttense morphology, clinicians should set up,
and prompt as needed, an elicitation context
that requires that the child utterance include a
subject. Doing so should more reliably reflect
skill in past-tense marking.
CONCLUSION
The principles for verb target selection
proposed by Crystal (1985) almost 30 years
ago have proven prescient when considered alongside more recent research on
acquisition of past-tense by children with and
without SLI. The broad Functional and Formal
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Verb Selection
categories he outlined, and the individual criteria therein, can serve as a helpful framework
for considering the clinical utility of emergent
findings (see summary outline of key ele-
161
ments in Table 2). Far from acting in isolation,
however, the myriad of potential verb-level
influences on past-tense marking likely
interact in complex and dynamic ways. The
Table 2. Examples of application of Crystal’s criteria to the selection of past-tense intervention
targets
Factor
More Facilitative
Less Facilitative
Lexical aspect1,2
+ Telic
He chewed up a raisin.
She crawled to her daddy.
− Telic
He chewed gum.
She crawled around the yard.
Inflected verb
frequency—Child3
High frequency verbs4 ending in Low frequency verbs4 ending in
nasals, stops, or fricatives and
nasals, stops, or fricatives and
marked with /t/ or /d/.
marked with /t/ or /d/
He opened the door.
He plugged the cord in.
She closed the door.
She sneezed loudly.
Inflected verb
frequency—Adult5
High frequency regular and
irregular verbs4
He baked a cake.
She fell off the chair.
Low frequency regular and irregular
verbs4
He peeled an orange.
She sent a letter.
Verb stem ending5,6
Phoneme other than /t/ or /d/
He broke the vase.
She played checkers.
Alveolar stops /t/ or /d/
He painted a picture.
She sat down.
Verb stem ending ×
inflected verb
frequency—Child3
Low frequency verbs4 ending in
a vowel or liquid and marked
with /d/
He filled the cup.
She cried for her mommy.
Low frequency verbs4 ending stops,
nasals, or fricatives and marked
with /t/ or /d/
He waved goodbye.
She danced in circles.
Irregular past-tense vowel Past dominant7
He ride → rode the horse.
change6
She find → found the keys.
Stem dominant7
He lead → led the race.
She grow → grew an inch.
Neighborhood structure6
Verbs from “friendly”
neighborhoods6
He feed → fed the horse.
She bleed → bled a little.
Verbs from “unfriendly”
neighborhoods6
He eat → ate an apple.
She meet → met the teacher.
Phonotactic probability
of past tense ending8
Monomorphemically legal
He tossed the ball.
She packed her bag.
Monomorphemically illegal
He hugged his sister.
She fished for trout.
Lexical aspect × verb
stem ending9
Activity category and
nonobstruent stem
He chewed on the rattle.
She crawled in circles.
Activity category and obstruent
stem
He skipped on the grass.
She jumped around the lawn.
Note. 1 Johnson & Fey, 2006; 2 Leonard et al., 2007; 3 Oetting & Horohov, 1997; 4 Hall, Nagy, & Linn, 1984; 5 Marchman,
Wulfeck, & Weismer, 1999; 6 Marchman, 1997; 7 Stemberger, 1993; 8 Marshall & van der Lely, 2006; 9 Johnson & Morris,
2007.
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162
TOPICS IN LANGUAGE DISORDERS/APRIL–JUNE 2013
likelihood of children’s use of past-tense morphology in obligatory contexts may best be
explained by the additive influence of several
properties of target verbs (Owen, 2010). For
example, past-tense morphology has been
shown to be influenced by a combination of
verb-level phonological and lexical aspect factors (Johnson & Morris, 2007). Accordingly, a
facilitative framework for learning past tense
might entail the clinician selecting verbs with
phonologically simple stem endings (i.e., a
liquid or vowel) and using them in action
contexts with clear endpoints (Oetting &
Hadley, 2008).
The obvious challenge facing clinicians, in
light of growing research in this arena, is
how best to incorporate complex findings
into their daily practice. Clinicians may benefit from a guiding reference for stimulus selection for past-tense interventions that builds
on the foundation established by Shipley and
Banis (1989) in their methods and materials
for Teaching Morphology Developmentally.
Such a treatment reference might group verb
targets for past tense (and, ideally, other morphemes and syntactic structures) according
to what current research indicates is more or
less facilitative of the target structure for typical language learners and, if different, children with language impairments. Table 2 provides a cursory illustration of how such a refer-
ence might be differentiated according to the
empirical application of Crystal’s criteria discussed in this article. A research-based guided
approach to the selection of past tense targets
would be more accessible than expecting individual clinicians to sift through numerous
research articles to identify relevant findings.
Similar to how a clinician might use 40,000
Selected Words: Organized by Letter, Sound,
and Syllable (Blockcolsky, Frazer, & Frazer,
1987) to inform his or her phonological interventions, examples of past tense targets by
criterion category could be selected from a
more exhaustive reference list and then customized on the basis of the individual needs,
goals, interests, or routines of the child.
Interventions targeting delayed morphological structures such as past tense, when
targeted within a functional communication context, are indicated by the literature
(Oetting & Hadley, 2008). If the primary purpose of evidence-based practice is to “help
clinicians make well-informed decisions about
treatment selection,” then failure to carefully
consider past-tense targets is to neglect an important body of evidence (Lof, 2011, p. 193).
This is consistent with Crystal’s (1985) counsel that “the question of deciding which
verbs to teach first, in a language-teaching
program, is too important to be left to
chance” (p. 48).
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