Publications

Abstract

Children with specific language impairment (SLI) have problems not only with language performance but also with sustained attention, which is the ability to maintain alertness over an extended period of time. Although there is consensus that this ability is impaired with respect to processing stimuli in the auditory perceptual modality, conflicting evidence exists concerning the visual modality.
Aims

To address the outstanding issue whether the impairment in sustained attention is limited to the auditory domain, or if it is domain-general. Furthermore, to test whether children's sustained attention ability relates to their word-production skills.
Methods & Procedures

Groups of 7–9 year olds with SLI (N = 28) and typically developing (TD) children (N = 22) performed a picture-naming task and two sustained attention tasks, namely auditory and visual continuous performance tasks (CPTs).
Outcomes & Results

Children with SLI performed worse than TD children on picture naming and on both the auditory and visual CPTs. Moreover, performance on both the CPTs correlated with picture-naming latencies across developmental groups.
Conclusions & Implications

These results provide evidence for a deficit in both auditory and visual sustained attention in children with SLI. Moreover, the study indicates there is a relationship between domain-general sustained attention and picture-naming performance in both TD and language-impaired children. Future studies should establish whether this relationship is causal. If attention influences language, training of sustained attention may improve language production in children from both developmental groups.

Abstract

Accumulating evidence suggests that spoken word production requires different amounts of top-down control depending on the prevailing circumstances. For example, during Stroop-like tasks, the interference in response time (RT) is typically larger following congruent trials than following incongruent trials. This effect is called the Gratton effect, and has been taken to reflect top-down control adjustments based on the previous trial type. Such control adjustments have been studied extensively in Stroop and Eriksen flanker tasks (mostly using manual responses), but not in the picture-word interference (PWI) task, which is a workhorse of language production research. In one of the few studies of the Gratton effect in PWI, Van Maanen and Van Rijn (2010) examined the effect in picture naming RTs during dual-task performance. Based on PWI effect differences between dual-task conditions, they argued that the functional locus of the PWI effect differs between post-congruent trials (i.e., locus in perceptual and conceptual encoding) and post-incongruent trials (i.e., locus in word planning). However, the dual-task procedure may have contaminated the results. We therefore performed an EEG study on the Gratton effect in a regular PWI task. We observed a PWI effect in the RTs, in the N400 component of the event-related brain potentials, and in the midfrontal theta power, regardless of the previous trial type. Moreover, the RTs, N400, and theta power reflected the Gratton effect. These results provide evidence that the PWI effect arises at the word planning stage following both congruent and incongruent trials, while the amount of top-down control changes depending on the previous trial type.

Abstract

Accumulating evidence suggests that spoken word production requires different amounts of top-down control depending on the prevailing circumstances. For example, during Stroop-like tasks, the interference in response time (RT) is typically larger following congruent trials than following incongruent trials. This effect is called the Gratton effect, and has been taken to reflect top-down control adjustments based on the previous trial type. Such control adjustments have been studied extensively in Stroop and Eriksen flanker tasks (mostly using manual responses), but not in the picture–word interference (PWI) task, which is a workhorse of language production research. In one of the few studies of the Gratton effect in PWI, Van Maanen and Van Rijn (2010) examined the effect in picture naming RTs during dual-task performance. Based on PWI effect differences between dual-task conditions, they argued that the functional locus of the PWI effect differs between post-congruent trials (i.e., locus in perceptual and conceptual encoding) and post-incongruent trials (i.e., locus in word planning). However, the dual-task procedure may have contaminated the results. We therefore performed an electroencephalography (EEG) study on the Gratton effect in a regular PWI task. We observed a PWI effect in the RTs, in the N400 component of the event-related brain potentials, and in the midfrontal theta power, regardless of the previous trial type. Moreover, the RTs, N400, and theta power reflected the Gratton effect. These results provide evidence that the PWI effect arises at the word planning stage following both congruent and incongruent trials, while the amount of top-down control changes depending on the previous trial type.

Abstract

Allocation and use of central processing capacity have been associated with the P3 event-related brain potential amplitude in a large variety of non-linguistic tasks. However, little is known about the P3 in spoken language production. Moreover, the few studies that are available report opposing P3 effects when task complexity is manipulated. We investigated allocation and use of central processing capacity in a spoken phrase production task: Participants switched every second trial between describing pictures using noun phrases with one adjective (size only; simple condition, e.g., “the big desk”) or two adjectives (size and color; complex condition, e.g., “the big red desk”). Capacity allocation was manipulated by complexity, and capacity use by switching. Response time (RT) was longer for complex than for simple trials. Moreover, complexity and switching interacted: RTs were longer on switch than on repeat trials for simple phrases but shorter on switch than on repeat trials for complex phrases. P3 amplitude increased with complexity. Moreover, complexity and switching interacted: The complexity effect was larger on the switch trials than on the repeat trials. These results provide evidence that the allocation and use of central processing capacity in language production are differentially reflected in the P3 amplitude.

Abstract

According to a prominent theory of language production, concepts activate multiple associated words in memory, which enter into competition for selection. However, only a few electrophysiological studies have identified brain responses reflecting competition. Here, we report a magnetoencephalography study in which the activation of competing words was manipulated by presenting pictures (e.g., dog) with distractor words. The distractor and picture name were semantically related (cat), unrelated (pin), or identical (dog). Related distractors are stronger competitors to the picture name because they receive additional activation from the picture relative to other distractors. Picture naming times were longer with related than unrelated and identical distractors. Phase-locked and non-phase-locked activity were distinct but temporally related. Phase-locked activity in left temporal cortex, peaking at 400 ms, was larger on unrelated than related and identical trials, suggesting differential activation of alternative words by the picture-word stimuli. Non-phase-locked activity between roughly 350–650 ms (4–10 Hz) in left superior frontal gyrus was larger on related than unrelated and identical trials, suggesting differential resolution of the competition among the alternatives, as reflected in the naming times. These findings characterise distinct patterns of activity associated with lexical activation and competition, supporting the theory that words are selected by competition.

Abstract

Disagreement exists regarding the functional locus of semantic interference of distractor words in picture naming. This effect is a cornerstone of modern psycholinguistic models of word production, which assume that it arises in lexical response-selection. However, recent evidence from studies of dual-task performance suggests a locus in perceptual or conceptual processing, prior to lexical response-selection. In these studies, participants manually responded to a tone and named a picture while ignoring a written distractor word. The stimulus onset asynchrony (SOA) between tone and picture–word stimulus was manipulated. Semantic interference in naming latencies was present at long tone pre-exposure SOAs, but reduced or absent at short SOAs. Under the prevailing structural or strategic response-selection bottleneck and central capacity sharing models of dual-task performance, the underadditivity of the effects of SOA and stimulus type suggests that semantic interference emerges before lexical response-selection. However, in more recent studies, additive effects of SOA and stimulus type were obtained. Here, we examined the discrepancy in results between these studies in 6 experiments in which we systematically manipulated various dimensions on which these earlier studies differed, including tasks, materials, stimulus types, and SOAs. In all our experiments, additive effects of SOA and stimulus type on naming latencies were obtained. These results strongly suggest that the semantic interference effect arises after perceptual and conceptual processing, during lexical response-selection or later. We discuss several theoretical alternatives with respect to their potential to account for the discrepancy between the present results and other studies showing underadditivity.

Abstract

Two fundamental factors affecting the speed of spoken word production are lexical frequency and sentential constraint, but little is known about their timing and electrophysiological basis. In the present study, we investigated event-related potentials (ERPs) and oscillatory brain responses induced by these factors, using a task in which participants named pictures after reading sentences. Sentence contexts were either constraining or nonconstraining towards the final word, which was presented as a picture. Picture names varied in their frequency of occurrence in the language. Naming latencies and electrophysiological responses were examined as a function of context and lexical frequency. Lexical frequency is an index of our cumulative learning experience with words, so lexical-frequency effects most likely reflect access to memory representations for words. Pictures were named faster with constraining than nonconstraining contexts. Associated with this effect, starting around 400 ms pre-picture presentation, oscillatory power between 8 and 30 Hz was lower for constraining relative to nonconstraining contexts. Furthermore, pictures were named faster with high-frequency than low-frequency names, but only for nonconstraining contexts, suggesting differential ease of memory access as a function of sentential context. Associated with the lexical-frequency effect, starting around 500 ms pre-picture presentation, oscillatory power between 4 and 10 Hz was higher for high-frequency than for low-frequency names, but only for constraining contexts. Our results characterise electrophysiological responses associated with lexical frequency and sentential constraint in spoken word production, and point to new avenues for studying these fundamental factors in language production.

Abstract

We investigated the neural basis of inhibitory control during lexical selection. Participants overtly named pictures while response times (RTs) and event-related brain potentials (ERPs) were recorded. The difficulty of lexical selection was manipulated by using object and action pictures with high name agreement (few response candidates) versus low name agreement (many response candidates). To assess the involvement of inhibition, we conducted delta plot analyses of naming RTs and examined the N2 component of the ERP. We found longer mean naming RTs and a larger N2 amplitude in the low relative to the high name agreement condition. For action naming we found a negative correlation between the slopes of the slowest delta segment and the difference in N2 amplitude between the low and high name agreement conditions. The converging behavioral and electrophysiological evidence suggests that selective inhibition is engaged to reduce competition during lexical selection in picture naming.

Abstract

The present study provides Dutch norms for age of acquisition, familiarity, imageability, image agreement, visual complexity, word frequency, and word length (in syllables) for 124 line drawings of actions. Ratings were obtained from 117 Dutch participants. Word frequency was determined on the basis of the SUBTLEX-NL corpus (Keuleers, Brysbaert, & New, Behavior Research Methods, 42, 643–650, 2010). For 104 of the pictures, naming latencies and name agreement were determined in a separate naming experiment with 74 native speakers of Dutch. The Dutch norms closely corresponded to the norms for British English. Multiple regression analysis showed that age of acquisition, imageability, image agreement, visual complexity, and name agreement were significant predictors of naming latencies, whereas word frequency and word length were not. Combined with the results of a principal-component analysis, these findings suggest that variables influencing the processes of conceptual preparation and lexical selection affect latencies more strongly than do variables influencing word-form encoding.

Abstract

Individuals speak incrementally when they interleave planning and articulation. Eyetracking, along with the measurement of speech onset latencies, can be used to gain more insight into the degree of incrementality adopted by speakers. In the current article, two eyetracking experiments are reported in which pairs of complex numerals were named (arabic format, Experiment 1) or read aloud (alphabetic format, Experiment 2) as house numbers and as clock times. We examined whether the degree of incrementality is differentially influenced by the production task (naming vs. reading) and mode (house numbers vs. clock time expressions), by comparing gaze durations and speech onset latencies. In both tasks and modes, dissociations were obtained between speech onset latencies (reflecting articulation) and gaze durations (reflecting planning), indicating incrementality. Furthermore, whereas none of the factors that determined gaze durations were reflected in the reading and naming latencies for the house numbers, the dissociation between gaze durations and response latencies for the clock times concerned mainly numeral length in both tasks. These results suggest that the degree of incrementality is influenced by the type of utterance (house number vs. clock time) rather than by task (reading vs. naming). The results highlight the importance of the utterance structure in determining the degree of incrementality.

Abstract

Does the spelling of a word mandatorily constrain spoken word production, or does it do so only
when spelling is relevant for the production task at hand? Damian and Bowers (2003) reported spelling
effects in spoken word production in English using a prompt–response word generation task. Preparation
of the response words was disrupted when the responses shared initial phonemes that differed
in spelling, suggesting that spelling constrains speech production mandatorily. The present experiments,
conducted in Dutch, tested for spelling effects using word production tasks in which spelling
was clearly relevant (oral reading in Experiment 1) or irrelevant (object naming and word generation
in Experiments 2 and 3, respectively). Response preparation was disrupted by spelling inconsistency
only with the word reading, suggesting that the spelling of a word constrains spoken word production
in Dutch only when it is relevant for the word production task at hand.

Abstract

In five language production experiments it was examined which aspects of words are activated in memory by context pictures and words. Context pictures yielded Stroop-like and semantic effects on response times when participants generated gender-marked noun phrases in response to written words (Experiment 1A). However, pictures yielded no such effects when participants simply read aloud the noun phrases (Experiment 2). Moreover, pictures yielded a gender congruency effect in generating gender-marked noun phrases in response to the written words (Experiments 3A and 3B). These findings suggest that context pictures activate lemmas (i.e., representations of syntactic properties), which leads to effects only when lemmas are needed to generate a response (i.e., in Experiments 1A, 3A, and 3B, but not in Experiment 2). Context words yielded Stroop-like and semantic effects in picture naming (Experiment 1B). Moreover, words yielded Stroop-like but no semantic effects in reading nouns (Experiment 4) and in generating noun phrases (Experiment 5). These findings suggest that context words activate the lemmas and forms of their names, which leads to semantic effects when lemmas are required for responding (Experiment 1B) but not when only the forms are required (Experiment 4). WEAVER++ simulations of the results are presented.

Abstract

Cognitive control includes the ability to formulate goals and plans of action and to follow these while facing distraction. Previous neuroimaging studies have shown that the presence of conflicting response alternatives in Stroop-like tasks increases activity in dorsal anterior cingulate cortex (ACC), suggesting that the ACC is involved in cognitive control. However, the exact nature of ACC function is still under debate. The prevailing conflict detection hypothesis maintains that the ACC is involved in performance monitoring. According to this view, ACC activity reflects the detection of response conflict and acts as a signal that engages regulative processes subserved by lateral prefrontal brain regions. Here, we provide evidence from functional MRI that challenges this view and favors an alternative view, according to which the ACC has a role in regulation itself. Using an arrow–word Stroop task, subjects responded to incongruent, congruent, and neutral stimuli. A critical prediction made by the conflict detection hypothesis is that ACC activity should be increased only when conflicting response alternatives are present. Our data show that ACC responses are larger for neutral than for congruent stimuli, in the absence of response conflict. This result demonstrates the engagement of the ACC in regulation itself. A computational model of Stroop-like performance instantiating a version of the regulative hypothesis is shown to account for our findings.

Abstract

Five chronometric experiments examined the functional architecture of naming dice, digits, and number words. Speakers named pictured dice, Arabic digits, or written number words, while simultaneously trying to ignore congruent or incongruent dice, digit, or number word distractors presented at various stimulus onset asynchronies (SOAs). Stroop-like interference and facilitation effects were obtained from digits and words on dice naming latencies, but not from dice on digit and word naming latencies. In contrast, words affected digit naming latencies and digits affected word naming latencies to the same extent. The peak of the interference was always around SOA = 0 ms, whereas facilitation was constant across distractor-first SOAs. These results suggest that digit naming is achieved like word naming rather than dice naming. WEAVER++simulations of the results are reported.

Abstract

Phonological encoding is the process by which speakers retrieve phonemic segments for morphemes from memory and use
the segments to assemble phonological representations of words to be spoken. When conversing in one language, bilingual
speakers have to resist the temptation of encoding word forms using the phonological rules and representations of the other
language. We argue that the activation of phonological representations is not restricted to the target language and that the
phonological representations of languages are not separate. We advance a view of bilingual control in which condition-action
rules determine what is done with the activated phonological information depending on the target language. This view is
computationally implemented in the WEAVER++ model. We present WEAVER++ simulations of the cognate facilitation effect
(Costa, Caramazza and Sebasti´an-Gall´es, 2000) and the between-language phonological facilitation effect of spoken
distractor words in object naming (Hermans, Bongaerts, de Bot and Schreuder, 1998).