Biomedical subjects

Ardi Roelofs

Publications and source records attributed to Ardi Roelofs.

14 recordsLinked to original sources

PubMed2006

Anterior cingulate cortex activity can be independent of response conflict in Stroop-like tasks.

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.

Adult↗

PubMed2006

Incrementality in naming and reading complex numerals: evidence from eyetracking.

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.

Electrooculography↗

PubMed2006

Context effects of pictures and words in naming objects, reading words, and generating simple phrases.

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.

Adult↗

PubMed2006

The influence of spelling on phonological encoding in word reading, object naming, and word generation.

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.

Association Learning↗

PubMed2005

The visual-auditory color-word stroop asymmetry and its time course.

Four experiments examined crossmodal versions of the Stroop task in order (1) to look for Stroop asymmetries in color naming, spoken-word naming, and written-word naming and to evaluate the time course of these asymmetries, and (2) to compare these findings to current models of the Stroop effect. Participants named color patches while ignoring spoken color words presented with an onset varying from 300 msec before to 300 msec after the onset of the color (Experiment 1), or they named the spoken words and ignored the colors (Experiment 2). A secondary visual detection task assured that the participants looked at the colors in both tasks. Spoken color words yielded Stroop effects in color naming, but colors did not yield an effect in spoken-word naming at any stimulus onset asynchrony. This asymmetry in effects was obtained with equivalent color- and spoken-word-naming latencies. Written color words yielded a Stroop effect in naming spoken words (Experiment 3), and spoken color words yielded an effect in naming written words (Experiment 4). These results were interpreted as most consistent with an architectural account of the color-word Stroop asymmetry, in contrast with discriminability and pathway strength accounts.

Adult↗

PubMed2004

Stem complexity and inflectional encoding in language production.

Three experiments are reported that examined whether stem complexity plays a role in inflecting polymorphemic words in language production. Experiment 1 showed that preparation effects for words with polymorphemic stems are larger when they are produced among words with constant inflectional structures compared to words with variable inflectional structures and simple stems. This replicates earlier findings for words with monomorphemic stems (Janssen et al., 2002). Experiments 2 and 3 showed that when inflectional structure is held constant, the preparation effects are equally large with simple and compound stems, and with compound and complex adjectival stems. These results indicate that inflectional encoding is blind to the complexity of the stem, which suggests that specific inflectional rather than generic morphological frames guide the generation of inflected forms in speaking words.

Humans↗

PubMed2004

Error biases in spoken word planning and monitoring by aphasic and nonaphasic speakers: comment on Rapp and Goldrick (2000).

B. Rapp and M. Goldrick (2000) claimed that the lexical and mixed error biases in picture naming by aphasic and nonaphasic speakers argue against models that assume a feedforward-only relationship between lexical items and their sounds in spoken word production. The author contests this claim by showing that a feedforward-only model like WEAVER++ (W. J. M. Levelt, A. Roelofs, & A. S. Meyer, 1999b) exhibits the error biases in word planning and self-monitoring. Furthermore, it is argued that extant feedback accounts of the error biases and relevant chronometric effects are incompatible. WEAVER++ simulations with self-monitoring revealed that this model accounts for the chronometric data, the error biases, and the influence of the impairment locus in aphasic speakers.

Aphasia↗

PubMed2004

Seriality of phonological encoding in naming objects and reading their names.

There is a remarkable lack of research bringing together the literatures on oral reading and speaking. As concerns phonological encoding, both models of reading and speaking assume a process of segmental spellout for words, which is followed by serial prosodification in models of speaking (e.g., Levelt, Roelofs, & Meyer, 1999). Thus, a natural place to merge models of reading and speaking would be at the level of segmental spellout. This view predicts similar seriality effects in reading and object naming. Experiment 1 showed that the seriality of encoding inside a syllable revealed in previous studies of speaking is observed for both naming objects and reading their names. Experiment 2 showed that both object naming and reading exhibit the seriality of the encoding of successive syllables previously observed for speaking. Experiment 3 showed that the seriality is also observed when object naming and reading trials are mixed rather than tested separately, as in the first two experiments. These results suggest that a serial phonological encoding mechanism is shared between naming objects and reading their names.

Humans↗

PubMed2003

Goal-referenced selection of verbal action: modeling attentional control in the Stroop task.

This article presents a new account of the color-word Stroop phenomenon (J. R. Stroop, 1935) based on an implemented model of word production, WEAVER++ (W. J. M. Levelt, A. Roelofs, & A. S. Meyer, 1999b; A. Roelofs, 1992, 1997c). Stroop effects are claimed to arise from processing interactions within the language-production architecture and explicit goal-referenced control. WEAVER++ successfully simulates 16 classic data sets, mostly taken from the review by C. M. MacLeod (1991), including incongruency, congruency, reverse-Stroop, response-set, semantic-gradient, time-course, stimulus, spatial, multiple-task, manual, bilingual, training, age, and pathological effects. Three new experiments tested the account against alternative explanations. It is shown that WEAVER++ offers a more satisfactory account of the data than other models.

Attention↗

PubMed2003

Planning levels in naming and reading complex numerals.

On the basis of evidence from studies of the naming and reading of numerals, Ferrand (1999) argued that the naming of objects is slower than reading their names, due to a greater response uncertainty in naming than in reading, rather than to an obligatory conceptual preparation for naming, but not for reading. We manipulated the need for conceptual preparation, while keeping response uncertainty constant in the naming and reading of complex numerals. In Experiment 1, participants named three-digit Arabic numerals either as house numbers or clock times. House number naming latencies were determined mostly by morphophonological factors, such as morpheme frequency and the number of phonemes, whereas clock time naming latencies revealed an additional conceptual involvement. In Experiment 2, the numerals were presented in alphabetic format and had to be read aloud. Reading latencies were determined mostly by morphophonological factors in both modes. These results suggest that conceptual preparation, rather than response uncertainty, is responsible for the difference between naming and reading latencies.

Humans↗

PubMed2002

Control of language use: cognitive modeling of the hemodynamics of Stroop task performance.

The control of language use has in its simplest form perhaps been most intensively studied using the color-word Stroop task. The authors review chronometric and neuroimaging evidence on Stroop task performance to evaluate two prominent, implemented models of control in naming and reading: GRAIN and WEAVER++. Computer simulations are reported, which reveal that WEAVER++ offers a more satisfactory account of the data than GRAIN. In particular, we report WEAVER++ simulations of the BOLD response in anterior cingulate cortex during Stroop performance. Aspects of single-word production and perception in the Stroop task are discussed in relation to the wider problem of the control of language use.

Animals↗

PubMed2002

Spoken language planning and the initiation of articulation.

Minimalist theories of spoken language planning hold that articulation starts when the first speech segment has been planned, whereas non-minimalist theories assume larger units (e.g., Levelt, Roelofs, & Meyer, 1999a). Three experiments are reported, which were designed to distinguish between these views using a new hybrid task that factorially manipulated preparation and auditory priming of spoken language production. Minimalist theories predict no effect from priming of non-initial segments when the initial segment of an utterance is already prepared; observing such a priming effect would support non-minimalist theories. In all three experiments, preparation and priming yielded main effects, and together their effects were additive. Preparation of initial segments does not eliminate priming effects for later segments. These results challenge the minimalist view. The findings are simulated by WEAVER++ (Roelofs, 1997b), which employs the phonological word as the lower limit for articulation initiation.

Adult↗

PubMed2002

Morphology by itself in planning the production of spoken words.

The authors report a study in Dutch that used an on-line preparation paradigm to test the issue of semantic dependency versus morphological autonomy in the production of polymorphemic words. Semantically transparent complex words (like input in English) and semantically opaque complex words (like invoice) showed clear evidence of morphological structure in word-form encoding, since both exhibited an equally large preparation effect that was much greater than that for morphologically simple words (like insect). These results suggest that morphemes may be planning units in the production of complex words, without making a semantic contribution, thereby supporting the autonomy view. Language production establishes itself as a domain in which morphology may operate "by itself' (Aronoff, 1994) without recourse to meaning.

Humans↗

PubMedDate not supplied

Naming analog clocks conceptually facilitates naming digital clocks.

This study investigates how speakers of Dutch compute and produce relative time expressions. Naming digital clocks (e.g., 2:45, say "quarter to three") requires conceptual operations on the minute and hour information for the correct relative time expression. The interplay of these conceptual operations was investigated using a repetition priming paradigm. Participants named analog clocks (the primes) directly before naming digital clocks (the targets). The targets referred to the hour (e.g., 2:00), half past the hour (e.g., 2:30), or the coming hour (e.g., 2:45). The primes differed from the target in one or two hour and in five or ten minutes. Digital clock naming latencies were shorter with a five- than with a ten-min difference between prime and target, but the difference in hour had no effect. Moreover, the distance in minutes had only an effect for half past the hour and the coming hour, but not for the hour. These findings suggest that conceptual facilitation occurs when conceptual transformations are shared between prime and target in telling time.

Cognition↗