Biomedical subjects

Derek Besner

Publications and source records attributed to Derek Besner.

At least 19 recordsLinked to original sources

PubMed2006

Parallel distributed processing and lexical-semantic effects in visual word recognition: are a few stages necessary?

D. C. Plaut and J. R. Booth (2000) presented a parallel distributed processing model that purports to simulate human lexical decision performance. This model (and D. C. Plaut, 1995) offers a single mechanism account of the pattern of factor effects on reaction time (RT) between semantic priming, word frequency, and stimulus quality without requiring a stages-of-processing account of additive effects. Three problems are discussed. First, no evidence is provided that this model can discriminate between words and nonwords with the same orthographic structure and still produce the pattern of factor effects on RT it currently claims to produce. Second, the level of representation used by the model to make a lexical decision is inconsistent with what is known about how skilled readers with damage to their semantic system make word/nonword discriminations. Finally, there are a number of results that are difficult to reconcile with the single mechanism account. The authors' preference is to retain the stages-of-processing account.

Humans↗

PubMed2006

Neighborhood effects in reading aloud: new findings and new challenges for computational models.

A word from a dense neighborhood is often read aloud faster than a word from a sparse neighborhood. This advantage is usually attributed to orthography, but orthographic and phonological neighbors are typically confounded. Two experiments investigated the effect of neighborhood density on reading aloud when phonological density was varied while orthographic density was held constant, and vice versa. A phonological neighborhood effect was observed, but not an orthographic one. These results are inconsistent with the predominant role ascribed to orthographic neighbors in accounts of visual word recognition and reading aloud. Consistent with this interpretation, 6 different computational models of reading aloud failed to simulate this pattern of results. The results of the present experiments thus provide a new understanding of some of the processes underlying reading aloud, and new challenges for computational models.

Attention↗

PubMed2005

The ties that keep us bound: Top-down influences on the persistence of shape-from-motion.

The phenomenon of perceptual persistence after the motion stops in shape-from-motion displays (SFM) was used to study the influence of prior knowledge on the maintenance of a percept in awareness. In SFM displays an object composed of discontinuous line segments are embedded in a background of randomly oriented lines. The object only becomes perceptible when the line segments that compose the object and the lines that compose the background move in counterphase. Critically, once the movement of the line segments stops, the percept of the object persists for a short period of time. In the present study, perceptual persistence for digits exceeded that reported for nonsense shapes composed of the same line segments. This result is taken as evidence that the processes involved in the persistence of SFM, and therefore sustained perception, are sensitive to top-down influences.

Adult↗

PubMed2005

Stroop dilution revisited: evidence for domain-specific, limited-capacity processing.

Nine experiments show that in the context of Stroop dilution the extent to which flanking distractors are processed depends on the nature of the material at fixation. A Stroop effect is eliminated if a word or a nonword is colored and appears at fixation and the color word appears as a flanker. A Stroop effect is observed when the color carrier at fixation is from a different domain than the color word distractor (e.g., Arabic digits). It is argued that when the material at fixation is in the same domain as the color word distractor, the distractor is not processed. Taken together, these results implicate a role for material-specific, limited-capacity processing in the context of this variant of the Stroop paradigm.

Attention↗

PubMed2005

Spatial attention as a necessary preliminary to early processes in reading.

One major theory of the relation between spatial attention and visual word recognition holds that the former is a necessary condition for the latter to begin. A different major theory asserts that although spatial attention can facilitate the latter, it is not a necessary condition. These two theories were pitted against each other experimentally. Spatial attention was operationalized in terms of the effect of a spatial precue on the time to name a target word that appeared above or below fixation. A masked prime word was presented before the target. The critical difference between experiments was cue validity (50% in Experiments 1a and 2a and 100% in Experiments 1b and 2b). Repetition priming was observed when the prime appeared in the uncued prime location in Experiments la and 2a but not in Experiments 1b or 2b. These results are inconsistent with the claim that visual word recognition does not depend on spatial attention. Discussion centres on the distribution of spatial attention across target locations as a function of cue validity.

Adolescent↗

PubMed2005

When the visual format of the color carrier word does and does not modulate the stroop effect.

We investigated the impact of making the color carrier word visually unfamiliar via case and font mixInG in the context of three Stroop experiments. Experiment 1 yielded an increase in the size of the Stroop effect when the color carrier words were visually unfamiliar relative to lowercase words that were case and font consistent. Experiments 2A and 2B showed that the modulation of the Stroop effect by visual familiarity observed in Experiment 1 was eliminated when there was no correlation between the color and the color carrier word. These results are considered in the light of four different theoretical accounts of the Stroop effect (strength of association [Cohen, Dunbar, & McClelland, 19901, instance [Logan, 1988], schema [MacLeod, 2000], and obligatory processing followed by deactivation [Coltheart, Woollams, Kinoshita, & Perry, 1999]). None of these accounts appear capable of explaining all the results.

Adult↗

PubMed2005

Contextual control over lexical and sublexical routines when reading english aloud.

Are the processes responsible for reading aloud single well-formed letter strings under contextual control? Despite the widespread contention that the answer to this question is "yes," it has been remarkably difficult to provide a compelling demonstration to that effect. In a speeded naming experiment, skilled readers read aloud exception words (such as PINT) that are atypical in terms of their spelling sound correspondences and nonwords (such as FLAD) that appeared in a predictable sequence. Subjects took longer to name both words and nonwords when the item on the preceding trial was from the other lexical category, relative to when the preceding item was from the same lexical category. This finding is consistent with the relative contributions of lexical and sublexical knowledge being controlled. We note a number of different ways that this control could arise and suggest some directions for future research.

Awareness↗

PubMed2005

Basic processes in reading: is visual word recognition obligatory?

Visual word recognition is commonly argued to be automatic in the sense that it is obligatory and ballistic. The present experiments combined Stroop and visual search paradigms to provide a novel test of this claim. An array of three, five, or seven words including one colored target (a word in Experiments 1 and 2, a bar in Experiment 3) was presented to participants. An irrelevant color word also appeared in the display and was either integrated with or separated from the colored target. The participants classified the color of the single colored item in Experiments 1 and 3 and determined whether a target color was present or absent in Experiment 2. A Stroop effect was observed in Experiment 1 when the color word and the color target were integral, but not when the color word and the color target were separated. No Stroop effect was observed in Experiment 2. Visual word recognition is contingent on both the distribution of spatial attention and task demands.

Attention↗

PubMed2005

Stimulus-response compatible orienting and the effect of an action not taken: perception delayed is automaticity denied.

Orienting to a signal source is widely viewed as automatic in the sense that it is triggered by the stimulus. However, this behavior is typically assessed in a context in which the subject knows beforehand what he or she has to do. In the present experiments, the role of task set was investigated by having the response vary randomly from trial to trial. On some trials, a cue signaled the subject to respond, and on the remaining trials, another cue signaled the subject to withhold a response. Stimulus contrast and temporal overlap between task cue and target were manipulated. The effect of a reduction in stimulus contrast was sometimes absorbed into the time taken to decode the cue, but critically, other times not. These results highlight the theoretical importance of considering task set as an essential element in processing, and they undermine the theoretical claim that putatively automatic processes are not subject to interference from other mental activities.

Automatism↗

PubMed2005

Basic processes in reading: a critical review of pseudohomophone effects in reading aloud and a new computational account.

There are pervasive lexical influences on the time that it takes to read aloud novel letter strings that sound like real words (e.g., brane from brain). However, the literature presents a complicated picture, given that the time taken to read aloud such items is sometimes shorter and sometimes longer than a control string (e.g.,frane) and that the time to read aloud is sometimes affected by the frequency of the base word and other times is not. In the present review, we first organize these data to show that there is considerably more consistency than has previously been acknowledged. We then consider six different accounts that have been proposed to explain various aspects of these data. Four of them immediately fail in one way or another. The remaining two accounts may be able to explain these findings, but they either make counterintuitive assumptions or invoke a novel mechanism solely to explain these findings. A new account is advanced that is able to explain all of the effects reviewed here and has none of the problems associated with the other accounts. According to this account, different types of lexical knowledge are used when pseudohomophones and nonword controls are read aloud in mixed and pure lists. This account is then implemented in Coltheart, Rastle, Perry, Langdon, and Ziegler's (2001) dual route cascaded model in order to provide an existence proof that it accommodates all of the effects, while retaining the ability to simulate three standard effects seen in nonword reading aloud.

Data Interpretation, Statistical↗

PubMed2005

A role for set when naming Arabic numerals: how intentionality limits (putatively automatic) performance.

Processing in various skilled domains is often described as automatic, in the sense that functional stimulus processing is triggered by stimulus onset and cannot be interrupted. One problem is that subjects typically know what task they have to perform prior to stimulus presentation. Various effects attributed to automatic processing may, therefore, arise instead from the mental set that is already in place. In the present study, we investigated skilled subjects' ability to engage in processing prior to knowing what the task is. A numeral was presented, and subjects either named it or added 1 and named the result. Which task was to be performed on a trial was signaled by a tone that appeared before or at the same time as the target. If functional target processing is triggered by its presentation, the effect of low contrast should be absorbed into the time taken to decode the task cue, regardless of the task (the effect of contrast should be absent at the 0-msec stimulus onset asynchrony [SOA] and present when task information is given in advance of the target). An underadditive interaction between contrast and SOA was seen for one task, but these factors had additive effects in the other task. This pattern can be understood in terms of the hypothesis that although encoding can be thought of as a stage common to both tasks, it is not, in the present context, functionally independent of a subsequent stage unique to a task.

Automatism↗

PubMed2004

In sight but out of mind: do competing views test the limits of perception without awareness?

Over a century's worth of research suggests that "perception" without awareness is a genuine phenomenon. However, relatively little research has explored the question of whether all visually presented information activates representations in long term memory without awareness. Two experiments explored the use of a figure-ground display consisting of competing views in which one view dominates the other such that subjects are (initially) unaware of the non-dominant view. Neither experiment provided evidence that the non-dominant view (an embedded word) activated its representation in long term memory when the subject failed to report being aware of the embedded word in that priming was not seen on a subsequent stem completion task. In contrast, priming was seen when subjects reported being aware of the embedded word. It is suggested that two competing figure-ground relations are not concurrently computed unconsciously.

Awareness↗

PubMed2004

Neighbourhood density, word frequency, and spelling-sound regularity effects in naming: similarities and differences between skilled readers and the Dual Route Cascaded Computational model.

An experiment with skilled readers and a series of simulations with the Dual Route Cascaded model (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001) investigated the joint effects of stimulus quality and Neighbourhood Density (N) in nonword naming. Neighbourhood Density and stimulus quality yielded additive effects on RT for skilled readers whereas the model produced an interaction between these factors. A further set of simulations show that DRC also produces an interaction between stimulus quality and (1) word frequency, (2) spelling-sound regularity, and, (3) nonword letter length. None of these three factors interact with stimulus quality in performance by skilled readers. It is suggested that DRC's assumption of cascaded processing throughout represents a central problem. A proposal as to how the model can be modified to accommodate these and other problematic data is discussed.

Humans↗

PubMed2004

On the control of visual word recognition: changing routes versus changing deadlines.

Two different accounts have been proposed to explain the fact that (1) an effect of word frequency is present when readers of transparent orthographies read only words aloud and (2) the effect of word frequency is eliminated when subjects name words and nonwords mixed together in a single block. In the route-shifting account, subjects shift from using a lexical route that can read only words to using a nonlexical route that can read both words and nonwords via the use of sublexical spelling-sound correspondences (hence, no word frequency effect). The essence of the second, time criterion account is that the elimination of the word frequency effect is determined by the speed with which the nonwords are processed, because subjects attempt to homogenize the point in time at which they release an articulation. These two different accounts are pitted against each other in a series of naming experiments utilizing the transparent Turkish orthography. A word frequency effect persists even when words and nonwords are mixed together, provided that nonword sets are matched so as to be named as quickly as the high-frequency words and as slowly as the low-frequency words, respectively. This result is argued to be consistent with the time criterion account, but not with the unadorned route-shifting account.

Humans↗

PubMed2004

Single letter coloring and spatial cuing eliminates a semantic contribution to the Stroop effect.

Previous work has shown that the Stroop effect is reduced in size when a single letter is colored and spatially precued. The present experiment addresses a number of criticisms of this work by (1) providing a direct measure of semantic processing, (2) using a vocal response instead of a manual one, and (3) using a more appropriate baseline. A semantically based Stroop effect (slower color naming for color-associated words than for color-neutral words) is observed when all letters in the display are precued and appear in a homogeneous color. This Stroop effect is statistically eliminated when a single letter is precued and is the "odd man out" in terms of its color. Two explanations are considered. In one, single-letter coloring and cuing serve to curtail semantic processing. In the other, single-letter coloring and cuing help to keep the informational sources (i.e, color, word) separate and hence reduce interference, but semantic analysis is not curtailed. The latter account provides a more complete account of existing data.

Color Perception↗

PubMed2003

A paradigm for exploring what the mind does while deciding what it should do.

One widespread belief about automatic mental processes is that, among other characteristics, they are involuntary. No initial conscious intent is necessary because such processing is stimulus initiated. This claim was studied in the context of a novel task-choice procedure in which subjects were informed as to which of two tasks they should perform on a letter string either well in advance of a target, or when the target appeared. The hypothesis that initial processing of the target occurs without intent predicts that the effect of contrast reduction will be absent when the task cue appears synchronously with the target. This is because initial processing of the target should be completed during the time taken to decode the task cue. The results are inconsistent with this account. Instead, they support an account in which functional target processing is delayed until the subject knows what the task is. Some directions for future investigations are noted.

Attention↗

PubMed2003

Reading nonwords aloud: results requiring change in the dual route cascaded model.

The time to name a nonword increases monotonically as letter length increases. The leading computational model of basic processes in reading (Coltheart, Rastle, Perry, Langdon & Ziegler's dual route cascaded model) simulates this, because its nonlexical route assigns phonemes to letters serially, left to right, and arguably, this corresponds to what humans do. New simulation work shows that (1) this letter length effect interacts with the effect of slowing the rate of early processing, and (2) the model produces a qualitatively different pattern from that observed with university-level readers. The contrast between simulation and human performance thus illuminates a problem with how the nonlexical route operates in the model, and constrains accounts that can be provided for the human data. Consideration is given to thresholding the output of the letter-level module as a way to modify the model so as to make it possible to simulate the human data.

Humans↗

PubMed2003

When parallel processing in visual word recognition is not enough: new evidence from naming.

Low-frequency irregular words are named more slowly and are more error prone than low-frequency regular words (the regularity effect). Rastle and Coltheart (1999) reported that this irregularity cost is modulated by the serial position of the irregular grapheme-phoneme correspondence, such that words with early irregularities exhibit a larger cost than words with late ones. They argued that these data implicate rule-based serial processing, and they also reported a successful simulation with a model that has a rule-based serial component--the DRC model of reading aloud (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). However, Zorzi (2000) also simulated these data with a model that operates solely in parallel. Furthermore, Kwantes and Mewhort (1999) simulated these data with a serial processing model that has no rules for converting orthography to phonology. The human data reported by Rastle and Coltheart therefore neither require a serial processing account, nor successfully discriminate among a number of computational models of reading aloud. New data are presented wherein an interaction between the effects of regularity and serial position of irregularity is again reported for human readers. The DRC model simulated this interaction; no other implemented computational model does so. The present results are thus consistent with rule-based serial processing in reading aloud.

Humans↗