Publications

Abstract

Word frequency plays a key role in theories of lexical access, which assume that the word frequency effect (WFE, faster access to high-frequency than low-frequency words) occurs as a result of differences in the representation and processing of the words. In a seminal paper, Jescheniak and Levelt (1994) proposed that the WFE arises during the retrieval of word forms, rather than the retrieval of their syntactic representations (their lemmas) or articulatory commands. An important part of Jescheniak and Levelt's argument was that they found a stable WFE in a picture naming task, which requires complete lexical access, but not in a gender decision task, which only requires access to the words' lemmas and not their word forms. We report two attempts to replicate this pattern, one with new materials, and one with Jescheniak and Levelt's orginal pictures. In both studies we found a strong WFE when the pictures were shown for the first time, but much weaker effects on their second and third presentation. Importantly these patterns were seen in both the picture naming and the gender decision tasks, suggesting that either word frequency does not exclusively affect word form retrieval, or that the gender decision task does not exclusively tap lemma access.

Abstract

n conversations, interlocutors concurrently perform two related processes: speech comprehension and speech planning. We investigated effects of speech planning on comprehension using EEG. Dutch speakers listened to sentences that ended with expected or unexpected target words. In addition, a picture was presented two seconds after target onset (Experiment 1) or 50 ms before target onset (Experiment 2). Participants’ task was to name the picture or to stay quiet depending on the picture category. In Experiment 1, we found a strong N400 effect in response to unexpected compared to expected target words. Importantly, this N400 effect was reduced in Experiment 2 compared to Experiment 1. Unexpectedly, the N400 effect was not smaller in the naming compared to categorization condition. This indicates that conceptual preparation or the decision whether to speak (taking place in both task conditions of Experiment 2) rather than processes specific to word planning interfere with comprehension.

Abstract

Turn-taking in everyday conversation is fast, with median latencies in corpora of conversational speech often reported to be under 300 ms. This seems like magic, given that experimental research on speech planning has shown that speakers need much more time to plan and produce even the shortest of utterances. This paper reviews how language scientists have combined linguistic analyses of conversations and experimental work to understand the skill of swift turn-taking and proposes a tentative solution to the riddle of fast turn-taking.

Abstract

To understand language, we need to recognize words and combine them into phrases and sentences. During this process, responses to the words themselves are changed. In a step towards understanding how the brain builds sentence structure, the present study concerns the neural readout of this adaptation. We ask whether low-frequency neural readouts associated with words change as a function of being in a sentence. To this end, we analyzed an MEG dataset by Schoffelen et al. (2019) of 102 human participants (51 women) listening to sentences and word lists, the latter lacking any syntactic structure and combinatorial meaning. Using temporal response functions and a cumulative model-fitting approach, we disentangled delta- and theta-band responses to lexical information (word frequency), from responses to sensory- and distributional variables. The results suggest that delta-band responses to words are affected by sentence context in time and space, over and above entropy and surprisal. In both conditions, the word frequency response spanned left temporal and posterior frontal areas; however, the response appeared later in word lists than in sentences. In addition, sentence context determined whether inferior frontal areas were responsive to lexical information. In the theta band, the amplitude was larger in the word list condition around 100 milliseconds in right frontal areas. We conclude that low-frequency responses to words are changed by sentential context. The results of this study speak to how the neural representation of words is affected by structural context, and as such provide insight into how the brain instantiates compositionality in language.

Abstract

Over the course of a conversation, interlocutors sound more and more like each other in a process called convergence. However, the automaticity and grain size of convergence are not well established. This study therefore examined whether female native Dutch speakers converge to large yet sub-phonemic shifts in the F2 of the vowel /e/. Participants first performed a short reading task to establish baseline F2s for the vowel /e/, then shadowed 120 target words (alongside 360 fillers) which contained one instance of a manipulated vowel /e/ where the F2 had been shifted down to that of the vowel /ø/. Consistent exposure to large (sub-phonemic) downward shifts in F2 did not result in convergence. The results raise issues for theories which view convergence as a product of automatic integration between perception and production.

Abstract

Language is used in communicative contexts to identify and successfully transmit new information that should be later remembered. In three studies, we used question–answer pairs, a naturalistic device for focusing information, to examine how properties of conversations inform later item memory. In Experiment 1, participants viewed three pictures while listening to a recorded question–answer exchange between two people about the locations of two of the displayed pictures. In a memory recognition test conducted online a day later, participants recognized the names of pictures that served as answers more accurately than the names of pictures that appeared as questions. This suggests that this type of focus indeed boosts memory. In Experiment 2, participants listened to the same items embedded in declarative sentences. There was a reduced memory benefit for the second item, confirming the role of linguistic focus on later memory beyond a simple serial-position effect. In Experiment 3, two participants asked and answered the same questions about objects in a dialogue. Here, answers continued to receive a memory benefit, and this focus effect was accentuated by language production such that information-seekers remembered the answers to their questions better than information-givers remembered the questions they had been asked. Combined, these studies show how people’s memory for conversation is modulated by the referential status of the items mentioned and by the speaker’s roles of the conversation participants.

Abstract

The relationship between the production and the comprehension systems has recently become a topic of interest for many psycholinguists. It has been argued that these systems are tightly linked and in particular that listeners use the production system to predict upcoming content. In this study, we tested how similar production and prediction processes are in a novel version of the visual world paradigm. Dutch speaking participants (native speakers in Experiment 1; German-Dutch bilinguals in Experiment 2) listened to mathematical equations while looking at a clock face featuring the numbers 1 to 12. On alternating trials, they either heard a complete equation ("three plus eight is eleven") or they heard the first part ("three plus eight is") and had to produce the result ("eleven") themselves. Participants were encouraged to look at the relevant numbers throughout the trial. Their eye movements were recorded and analyzed. We found that the participants' eye movements in the two tasks were overall very similar. They fixated the first and second number of the equations shortly after they were mentioned, and fixated the result number well before they named it on production trials and well before the recorded speaker named it on comprehension trials. However, all fixation latencies were shorter on production than on comprehension trials. These findings suggest that the processes involved in planning to say a word and anticipating hearing a word are quite similar, but that people are more aroused or engaged when they intend to respond than when they merely listen to another person.

Abstract

Whereas it has long been assumed that most linguistic processes underlying language production happen automatically, accumulating evidence suggests that some form of attention is required. Here, we investigated the contribution of sustained attention, which is the ability to maintain alertness over time. First, the sustained attention ability of participants was measured using auditory and visual continuous performance tasks. Next, the participants described pictures using simple noun phrases while their response times (RTs) and gaze durations were measured. Earlier research has suggested that gaze duration reflects language planning processes up to and including phonological encoding. Individual differences in sustained attention ability correlated with individual differences in the magnitude of the tail of the RT distribution, reflecting the proportion of very slow responses, but not with individual differences in gaze duration. These results suggest that language production requires sustained attention, especially after phonological encoding.

Abstract

It has previously been shown that language production, performed simultaneously with a nonlinguistic task, involves sustained attention. Sustained attention concerns the ability to maintain alertness over time. Here, we aimed to replicate the previous finding by showing that individuals call upon sustained attention when they plan single noun phrases (e.g., "the carrot") and perform a manual arrow categorization task. In addition, we investigated whether speakers also recruit sustained attention when they produce conjoined noun phrases (e.g., "the carrot and the bucket") describing two pictures, that is, when both the first and second task are linguistic. We found that sustained attention correlated with the proportion of abnormally slow phrase-production responses. Individuals with poor sustained attention displayed a greater number of very slow responses than individuals with better sustained attention. Importantly, this relationship was obtained both for the production of single phrases while performing a nonlinguistic manual task, and the production of noun phrase conjunctions in referring to two spatially separated objects. Inhibition and updating abilities were also measured. These scores did not correlate with our measure of sustained attention, suggesting that sustained attention and executive control are distinct. Overall, the results suggest that planning conjoined noun phrases involves sustained attention, and that language production happens less automatically than has often been assumed.

Abstract

Frequent and predictable words are generally pronounced with less effort and are therefore acoustically more reduced than less frequent or unpredictable words. Local predictability can be operationalised by Transitional Probability (TP), which indicates how likely a word is to occur given its immediate context. We investigated whether and how probabilistic reduction effects on word durations change with adult age when reading aloud content words embedded in sentences. The results showed equally large frequency effects on verb and noun durations for both younger (Mage = 20 years) and older (Mage = 68 years) adults. Backward TP also affected word duration for younger and older adults alike. ForwardTP, however, had no significant effect on word duration in either age group. Our results resemble earlier findings of more robust BackwardTP effects compared to ForwardTP effects. Furthermore, unlike often reported decline in predictive processing with aging, probabilistic reduction effects remain stable across adulthood.

Abstract

During language comprehension, listeners often anticipate upcoming information. This can draw listeners’ overt attention to visually presented objects before the objects are referred to. We investigated to what extent the anticipatory mechanisms involved in such language-mediated attention rely on specific verbal factors and on processes shared with other domains of cognition. Participants listened to sentences ending in a highly predictable word (e.g., “In 1969 Neil Armstrong was the first man to set foot on the moon”) while viewing displays containing three unrelated distractor objects and a critical object, which was either the target object (e.g., a moon), or an object with a similar shape (e.g., a tomato), or an unrelated control object (e.g., rice). Language-mediated anticipatory eye movements to targets and shape competitors were observed. Importantly, looks to the shape competitor were systematically related to individual differences in anticipatory attention, as indexed by a spatial cueing task: Participants whose responses were most strongly facilitated by predictive arrow cues also showed the strongest effects of predictive language input on their eye movements. By contrast, looks to the target were related to individual differences in vocabulary size and verbal fluency. The results suggest that verbal and nonverbal factors contribute to different types of language-mediated eye movement. The findings are consistent with multiple-mechanism accounts of predictive language processing.

Abstract

In different tasks involving action perception, performance has been found to be facilitated
when the presented stimuli were produced by the participants themselves rather than by
another participant. These results suggest that the same mental representations are
accessed during both production and perception. However, with regard to spoken word perception,
evidence also suggests that listeners’ representations for speech reflect the input
from their surrounding linguistic community rather than their own idiosyncratic productions.
Furthermore, speech perception is heavily influenced by indexical cues that may lead listeners
to frame their interpretations of incoming speech signals with regard to speaker identity.
In order to determine whether word recognition evinces similar self-advantages as found in
action perception, it was necessary to eliminate indexical cues from the speech signal. We therefore asked participants to identify noise-vocoded versions of Dutch words that were based on either their own recordings or those of a statistically average speaker. The majority of participants were more accurate for the average speaker than for themselves, even after taking into account differences in intelligibility. These results suggest that the speech
representations accessed during perception of noise-vocoded speech are more reflective
of the input of the speech community, and hence that speech perception is not necessarily based on representations of one’s own speech.

Abstract

In two studies, we examined whether explicit distractors are necessary and sufficient toevoke selective inhibition in three naming tasks: the semantic blocking, picture-word interference, and color-word Stroop task. Delta plots were used to quantify the size of the interference effects as a function of reaction time (RT). Selective inhibition was operationalized as the decrease in the size of the interference effect as a function of naming RT. For all naming tasks, mean naming RTs were significantly longer in the interference condition than in a control condition. The slopes of the interference effects for the longest naming RTs correlated with the magnitude of the mean interference effect in both the semantic blocking task and the picture-word interference task, suggesting that selective inhibition was involved to reduce the interference from strong semantic competitors either invoked by a single explicit competitor or strong implicit competitors in picture naming. However, there was no correlation between the slopes and the mean interference effect in the Stroop task, suggesting less importance of selective inhibition in this task despite explicit distractors. Whereas the results of the semantic blocking task suggest that an explicit distractor is not necessary for triggering inhibition, the results of the Stroop task suggest that such a distractor is not sufficient for evoking inhibition either.

Abstract

The smooth transitions between turns in natural conversation suggest that speakers often begin to plan their utterances while listening to their interlocutor. The presented study investigates whether this is indeed the case and, if so, when utterance planning begins. Two hypotheses were contrasted: that speakers begin to plan their turn as soon as possible (in our experiments less than a second after the onset of the interlocutor’s turn), or that they do so close to the end of the interlocutor’s turn. Turn-taking was combined with a finger tapping task to measure variations in cognitive load. We assumed that the onset of speech planning in addition to listening would be accompanied by deterioration in tapping performance. Two picture description experiments were conducted. In both experiments there were three conditions: (1) Tapping and Speaking, where participants tapped a complex pattern while taking over turns from a pre-recorded speaker, (2) Tapping and Listening, where participants carried out the tapping task while overhearing two pre-recorded speakers, and (3) Speaking Only, where participants took over turns as in the Tapping and Speaking condition but without tapping. The experiments differed in the amount of tapping training the participants received at the beginning of the session. In Experiment 2, the participants’ eye-movements were recorded in addition to their speech and tapping. Analyses of the participants’ tapping performance and eye movements showed that they initiated the cognitively demanding aspects of speech planning only shortly before the end of the turn of the preceding speaker. We argue that this is a smart planning strategy, which may be the speakers’ default in many everyday situations.

Abstract

An important issue in current psycholinguistics is how the time course of utterance planning affects the generation of grammatical structures. The current study investigated the influence of parallel activation of the components of complex noun phrases on the generation of subject-verb agreement. Specifically, the lexical interference account (Gillespie, M. and Pearlmutter, N. J., 2011b and Solomon, E. S. and Pearlmutter, N. J., 2004) predicts more agreement errors (i.e., attraction) for subject phrases in which the head and local noun mismatch in number (e.g., the apple next to the pears) when nouns are planned in parallel than when they are planned in sequence. We used a speeded picture description task that yielded sentences such as the apple next to the pears is red. The objects mentioned in the noun phrase were either semantically related or unrelated. To induce agreement errors, pictures sometimes mismatched in number. In order to manipulate the likelihood of parallel processing of the objects and to test the hypothesized relationship between parallel processing and the rate of agreement errors, the pictures were either placed close together or far apart. Analyses of the participants' eye movements and speech onset latencies indicated slower processing of the first object and stronger interference from the related (compared to the unrelated) second object in the close than in the far condition. Analyses of the agreement errors yielded an attraction effect, with more errors in mismatching than in matching conditions. However, the magnitude of the attraction effect did not differ across the close and far conditions. Thus, spatial proximity encouraged parallel processing of the pictures, which led to interference of the associated conceptual and/or lexical representation, but, contrary to the prediction, it did not lead to more attraction errors.

Abstract

We investigated the time course of conjunctive ''same''-''different'' judgements for visually presented object pairs by means of combined reaction time and on-line eye movement measurements. The analyses of viewing patterns, viewing times, and reaction times showed that participants engaged in a parallel self-terminating search for differences. In addition, the results obtained for objects differing in only one dimension suggest that processing times may depend on the relative codability of the stimulus dimensions. The results are reviewed in a broader framework in view of higher-order processes. We propose that overspecifications of colour, often found in object descriptions, may have an ''early'' visual rather than a ''late'' linguistic origin. In a parallel assessment of the detection materials, participants overspecified the objects' colour substantially more often than their size. We argue that referential overspecifications of colour are largely attributable to mechanisms of visual discrimination.

Abstract

The study investigated the neuronal basis of the retrieval of words from the mental lexicon. The semantic category interference effect was used to locate lexical retrieval processes in time and space. This effect reflects the finding that, for overt naming, volunteers are slower when naming pictures out of a sequence of items from the same semantic category than from different categories. Participants named pictures blockwise either in the context of same- or mixedcategory items while the brain response was registered using magnetoencephalography (MEG). Fifteen out of 20 participants showed longer response latencies in the same-category compared to the mixed-category condition. Event-related MEG signals for the participants demonstrating the interference effect were submitted to a current source density (CSD) analysis. As a new approach, a principal component analysis was applied to decompose the grand average CSD distribution into spatial subcomponents (factors). The spatial factor indicating left temporal activity revealed significantly different activation for the same-category compared to the mixedcategory condition in the time window between 150 and 225 msec post picture onset. These findings indicate a major involvement of the left temporal cortex in the semantic interference effect. As this effect has been shown to take place at the level of lexical selection, the data suggest that the left temporal cortex supports processes of lexical retrieval during production.