Presentations

Abstract

Individual differences in language processing are prevalent in our daily lives. However, for decades, psycholinguistic research has largely ignored variation in the normal range of abilities. Recently, scientists have begun to acknowledge the importance of inter-individual variability for a comprehensive characterization of the language system. In spite of this change of attitude, empirical research on individual differences is still sparse, which is in part due to the lack of a suitable research tool. Here, we present a novel battery of behavioral tests for assessing individual differences in language skills in younger adults. The Dutch prototype comprises 29 subtests and assesses many aspects of language knowledge (grammar and vocabulary), linguistic processing skills (word and sentence level) and general cognitive abilities involved in using language (e.g., WM, IQ). Using the battery, researchers can determine performance profiles for individuals and link them to neurobiological or genetic data.

Abstract

It is evident that speakers can freely vary stylistic features of their speech, such as speech rate, but how they accomplish this has hardly been studied, let alone implemented in a formal model of speech production. Much as in walking and running, where qualitatively different gaits are required cover the gamut of different speeds, we might predict there to be multiple qualitatively distinct configurations, or ‘gaits’, in the speech planning system that speakers must switch between to alter their speaking rate or style. Alternatively, control might involve continuous modulation of a single ‘gait’. We investigate these possibilities by simulation of a connectionist computational model which mimics the temporal characteristics of observed speech. Different ‘regimes’ (combinations of parameter settings) can be engaged to achieve different speaking rates.

The model was trained separately for each speaking rate, by an evolutionary optimisation algorithm. The training identified parameter values that resulted in the model to best approximate syllable duration distributions characteristic of each speaking rate.

In one gait system, the regimes used to achieve fast and slow speech are qualitatively similar, but quantitatively different. In parameter space, they would be arranged along a straight line. Different points along this axis correspond to different speaking rates. In a multiple gait system, this linearity would be missing. Instead, the arrangement of the regimes would be triangular, with no obvious relationship between the regions associated with each gait, and an abrupt shift in parameter values to move from speeds associated with ‘walk-speaking’ to ‘run-speaking’.

Our model achieved good fits in all three speaking rates. In parameter space, the arrangement of the parameter settings selected for the different speaking rates is non-axial, suggesting that ‘gaits’ are present in the speech planning system.

Abstract

It is unknown whether modality affects the efficiency with which we learn novel word forms and their meanings. In this study, 60 participants were trained on 24 pseudowords, each paired with a pictorial meaning (novel object). Following a 20 minute filler task participants were tested on their ability to identify the picture-word form pairs on which they were trained when presented amongst foils. Word forms were presented in either their written or spoken form, with exposure to the written form equal to the speech duration of the spoken form. The between subjects design generated four participant groups 1) written training, written test; 2) written training, spoken test; 3) spoken training, written test; 4) spoken training, spoken test. Our results show a written training advantage: participants trained on written words were more accurate on the matching task. An ongoing follow-up experiment tests whether the written advantage is caused by additional time with the full word form, given that words can be read faster than the time taken for the spoken form to unfold. To test this, in training, written words were presented with sufficient time for participants to read, yet maximally half the duration of the spoken form in experiment 1.

Abstract

It is unknown whether modality affects the efficiency with which humans learn novel word forms and their meanings, with previous studies reporting both written and auditory advantages. The current study implements controls whose absence in previous work likely offers explanation for such contradictory findings. In two novel word learning experiments, participants were trained and tested on pseudoword - novel object pairs, with controls on: modality of test, modality of meaning, duration of exposure and transparency of word form. In both experiments word forms were presented in either their written or spoken form, each paired with a pictorial meaning (novel object). Following a 20-minute filler task, participants were tested on their ability to identify the picture-word form pairs on which they were trained. A between subjects design generated four participant groups per experiment 1) written training, written test; 2) written training, spoken test; 3) spoken training, written test; 4) spoken training, spoken test. In Experiment 1 the written stimulus was presented for a time period equal to the duration of the spoken form. Results showed that when the duration of exposure was equal, participants displayed a written training benefit. Given words can be read faster than the time taken for the spoken form to unfold, in Experiment 2 the written form was presented for 300 ms, sufficient time to read the word yet 65% shorter than the duration of the spoken form. No modality effect was observed under these conditions, when exposure to the word form was equivalent. These results demonstrate, at least for proficient readers, that when exposure to the word form is controlled across modalities the efficiency with which word form-meaning associations are learnt does not differ. Our results therefore suggest that, although we typically begin as aural-only word learners, we ultimately converge on developing learning mechanisms that learn equally efficiently from both written and spoken materials.

Abstract

It is unknown whether modality affects the efficiency with which humans learn novel word forms and their meanings, with previous studies reporting both written and auditory advantages. The current study implements controls whose absence in previous work likely offers explanation for such contradictory findings. In two novel word learning experiments, participants were trained and tested on pseudoword - novel object pairs, with controls on: modality of test, modality of meaning, duration of exposure and transparency of word form. In both experiments word forms were presented in either their written or spoken form, each paired with a pictorial meaning (novel object). Following a 20-minute filler task, participants were tested on their ability to identify the picture-word form pairs on which they were trained. A between subjects design generated four participant groups per experiment 1) written training, written test; 2) written training, spoken test; 3) spoken training, written test; 4) spoken training, spoken test. In Experiment 1 the written stimulus was presented for a time period equal to the duration of the spoken form. Results showed that when the duration of exposure was equal, participants displayed a written training benefit. Given words can be read faster than the time taken for the spoken form to unfold, in Experiment 2 the written form was presented for 300 ms, sufficient time to read the word yet 65% shorter than the duration of the spoken form. No modality effect was observed under these conditions, when exposure to the word form was equivalent. These results demonstrate, at least for proficient readers, that when exposure to the word form is controlled across modalities the efficiency with which word form-meaning associations are learnt does not differ. Our results therefore suggest that, although we typically begin as aural-only word learners, we ultimately converge on developing learning mechanisms that learn equally efficiently from both written and spoken materials.

Abstract

Studies on the generation effect have found that coming up with words, compared to reading them, improves memory. However, because these studies used words at both study and test, it is unclear whether generation affects visual or conceptual/lexical representations. Here, participants named pictures after hearing the picture name (no-generation condition), backward speech, or an unrelated word (easy and harder generation conditions). We ruled out effects at the visual level by testing participants’ recognition memory on the written names of the pictures that were named earlier. We also assessed the effect of processing time during generation on memory. In the recognition memory test, participants were more accurate in the generation conditions than in the no-generation condition. They were also more accurate for words that took longer to be retrieved, but only when generation was required. This work shows that generation affects conceptual/lexical representations and informs the relationship between language and memory.

Abstract

Conversation often involves simultaneous production and comprehension, yet little research has investigated whether these two processes interfere with one another. We tested participants’ ability to dual-task with production and comprehension tasks. Task one (production task) was picture naming. Task two (comprehension task) was either syllable identification (linguistic condition) or tone identification (non-linguistic condition). The two identification tasks were matched for difficulty. Three SOAs (50ms, 300ms, and 1800ms) resulted in different amounts of overlap between the production and comprehension tasks. We hypothesized that as production and comprehension use similar resources there would be greater interference with concurrent linguistic than non-linguistic tasks.
At the 50ms SOA, picture naming latencies were slower in the linguistic compared to the non-linguistic condition, suggesting that the resources required for production and comprehension overlap more in the linguistic condition. As the syllables were non-words without lexical representations, this interference likely occurs primarily at the phonological level. Across all SOAs, identification RTs were longer in the linguistic condition, showing that such phonological interference percolates through to the comprehension task, regardless of SOA. In sum, these results demonstrate that concurrent access to the phonological level in production and comprehension results in measurable interference in both speaking and comprehending.

Abstract

Listeners are continuously exposed to a broad range of speech rates. Earlier work has shown that listeners perceive phonetic category boundaries relative to contextual speech rate. This process of rate-dependent speech perception has been suggested to occur across talker changes, with the speech rate of talker A influencing perception of talker B. This study tested whether a ‘global’ speech rate calculated over multiple talkers and over a longer period of time affected perception of the temporal Dutch vowel contrast /ɑ/-/a:/. First, Experiment 1 demonstrated that listeners more often reported hearing long /a:/ in fast contexts than in ‘neutral rate’ contexts, replicating earlier findings. Then, in Experiment 2, one participant group was exposed to ‘neutral’ speech from talker A intermixed with slow speech from talker B. Another group listened to the same ‘neutral’ speech from talker A, but to fast speech from talker B. Between-group comparison in the ‘neutral’ condition revealed that Group 1 reported more long /a:/ than Group 2, indicating that A’s ‘neutral’ speech sounded faster when B was slower. Finally, Experiment 3 tested whether talking at slow or fast rates oneself elicits the same ‘global’ rate effects. However, no evidence was found that self-produced speech modulated perception of talker A. This study corroborates the idea that ‘global’ rate-dependent effects occur across talkers, but are insensitive to one’s own speech rate. Results are interpreted in light of the general auditory mechanisms thought to underlie rate normalization, with implications for our understanding of dialogue.

Abstract

Speech rate is known to modulate perception of temporally ambiguous speech sounds. For instance, a vowel may be perceived as short when the immediate speech context is slow, but as long when the context is fast. Yet, effects of long-term tracking of speech rate are largely unexplored. Two experiments tested whether long-term tracking of rate influences perception of the temporal Dutch vowel contrast /A/-/a:/. In Experiment 1, one low-rate group listened to ‘neutral’ rate speech from talker A and to slow speech from talker B. Another high-rate group was exposed to the same neutral speech from A, but to fast speech from B. Between-group comparison of the ‘neutral’ trials revealed that the low-rate group reported a higher proportion of /a:/ in A’s ‘neutral’ speech, indicating that A sounded faster when B was slow. Experiment 2 tested whether one’s own speech rate also contributes to effects of long-term tracking of rate. Here, talker B’s speech was replaced by playback of participants’ own fast or slow speech. No evidence was found that one’s own voice affected perception of talker A in larger speech contexts. These results carry implications for our understanding of the mechanisms involved in rate-dependent speech perception and of dialogue.

Abstract

Speech rate is known to modulate perception of temporally ambiguous speech sounds. For instance, a vowel may be perceived as short when the immediate speech context is slow, but as long when the context is fast. Yet, effects of long-term tracking of speech rate are largely unexplored. Two experiments tested whether long-term tracking of rate influences perception of the temporal Dutch vowel contrast /ɑ/-/a:/. In Experiment 1, one low-rate group listened to 'neutral' rate speech from talker A and to slow speech from talker B. Another high-rate group was exposed to the same neutral speech from A, but to fast speech from B. Between-group comparison of the 'neutral' trials revealed that the low-rate group reported a higher proportion of /a:/ in A's 'neutral' speech, indicating that A sounded faster when B was slow. Experiment 2 tested whether one's own speech rate also contributes to effects of long-term tracking of rate. Here, talker B's speech was replaced by playback of participants' own fast or slow speech. No evidence was found that one's own voice affected perception of talker A in larger speech contexts. These results carry implications for our understanding of the mechanisms involved in rate-dependent speech perception and of dialogue.

Abstract

Speech can be produced at different rates. The ability to produce faster or slower speech may be thought to result from executive control processes enlisted to modulate lexical selection and phonological encoding stages of speech planning.

This study used simulations of the model of serial order in language by Dell, Burger and Svec (1997, DBS) to characterise the strategies adopted by speakers when naming pictures at fast, medium and slow prescribed rates. Our new implementation of DBS was able to produce activation patterns that correlated strongly with observed syllable-level timing of disyllabic words from this task.

For each participant, different speaking rates were associated with different regions of the DBS parameter space. The precise placement of the speaking rates in the parameter space differed markedly between participants. Participants applied broadly the same parameter manipulation to accelerate their speech. This was however not the case for deceleration. Hierarchical clustering revealed two distinct patterns of parameter adjustment employed to decelerate speech, suggesting that deceleration is not necessarily achieved by the inverse process of acceleration. In addition, potential refinements to the DBS model are discussed.