Semantic processing of crowded stimuli?

Effects of semantic processing of crowded characters were investigated using numbers as stimuli. In an identification task, typical spacing effects in crowding were replicated. Using the same stimuli in a magnitude comparison task, a smaller effect of spacing was observed as well as an effect of response congruency. These effects were replicated in a second experiment with varying stimulus-onset asynchronies. In addition, decreasing performance with increasing onset-asynchrony (so-called type-B masking) for incongruent flankers indicates semantic processing of target and flankers. The data show that semantic processing takes place even in crowded stimuli. This argues strongly against common accounts of crowding in terms of early stimulus-driven impairments of processing.     

When do children overestimate their knowledge of unfamiliar targets?

We report four investigations in which 5 to 7 year olds judged whether or not they knew familiar- and unfamiliar-named targets. Under some conditions judgments were made in relation to performance on a relevant task, e.g., children judged whether they knew the picture they had picked from a set was the target. Under other conditions, children judged their state of knowledge not in relation to performance, e.g., they answered "Do you know who (target) is?" Under both types of condition, children nearly always made correct "know" judgments when targets were familiar. Correct "don't know" judgments about unfamiliar targets were relatively common when judgments were not made in relation to performance on a task (average scores 80-90% correct), but were less frequent when knowledge was judged in relation to performance on a task (average scores 40-70% correct). Knowledge judged in relation to performance was overestimated even when children did not choose the picture they thought might be the target before making their judgment, when the pictures were face-down, and when children predicted performance on a task not yet present. It seems that although children can make relatively accurate judgments of their own knowledge states, they tend to overestimate their competence when assessing their knowledge in relation to performance on a task. We discuss why this might be.     

Does negative priming imply preselective identification of irrelevant stimuli?

Responses to recently ignored stimuli are often slower than responses to new stimuli (negative priming). This slowing is thought to imply that the irrelevant stimuli were identified before the relevant stimuli were selected. The slowing may, however, reflect processing that occurred after the selection process had already begun. In two experiments, the opportunity for preselective identification of irrelevant stimuli was eliminated by presenting the irrelevant stimuli late within the trial. Negative priming failed to occur under these conditions.     

When do spatial and visual working memory interact?

This study examined how spatial working memory and visual (object) working memory interact, focusing on two related questions: First, can these systems function independently from one another? Second, under what conditions do they operate together? In a dual-task paradigm, participants attempted to remember locations in a spatial working memory task and colored objects in a visual working memory task. Memory for the locations and objects was subject to independent working memory storage limits, which indicates that spatial and visual working memory can function independently from one another. However, additional experiments revealed that spatial working memory and visual working memory interact in three memory contexts: when retaining (1) shapes, (2) integrated color-shape objects, and (3) colored objects at specific locations. These results suggest that spatial working memory is needed to bind colors and shapes into integrated object representations in visual working memory. Further, this study reveals a set of conditions in which spatial and visual working memory can be isolated from one another.     

Target redundancy in visual search: Do repetitions of the target within thedisplay impair processing?

Two experiments tested the predictions from Bjork and Murray’s (1977) extension of Estes’ (1972, 1974) interactive channels model that repetition of a target within a display should, under certain conditions, impair or slow processing. These predictions were contrasted with those of the continuous flow model (Eriksen & Schultz, 1979) that, under the same conditions, repetitions should not impair processing and might possibly facilitate it. Experiment 1 evaluated the relative effects of feature similarity, variable target-noise spacing, and perceptual segregation in a response competition paradigm. In general, results favored the continuous flow conception and competition among internal recognition responses, and no evidence was found for impaired performance due to target repetitions. However, questions concerning possible facilitation arising from redundancy led to Experiment 2. In that experiment, trials were blocked by spacing or noise type. Again, target redundancy did not impair performance relative to the single target control. However, no facilitation effects were found.     

When do nonwords activate semantics? Implications for models of visual word recognition

Three lexical decision experiments examined the conditions in which nonwords activate semantics. Lexical decisions to targets (e.g., CAT) were faster when preceded by semantically related nonword primes (e.g., DEG derived from DOG) when the prime was brief and masked; this nonword priming effect was eliminated when the prime was presented for a longer duration. These results are discussed in the context of both parallel distributed processing models and the idea that the occurrence of nonword priming depends upon subjects being unable to verify the identity of the prime.     

When are semantic targets detected faster than visual or acoustic ones?

Duration-discrimination data from an experiment using empty auditory intervals in a two-alternative forced-choice paradigm are presented. The observed functional relationship between standard deviation of the psychometric density function and stimulus duration is shown to be fit significantly better by a Weber’s law model of duration discrimination than by Creelman’s counter model. Both models fail to predict the rapid rise in the Weber fraction observed for durations longer than about 2 sec. However, the Weber’s law model, based on a generalization of Weber’s law, accurately predicts the initial drop in the Weber fraction for very short durations and the observed constancy of the Weber fraction for durations up to 2 sec.     

When do auditory/visual differences in duration judgements occur?

Four experiments examined judgements of the duration of auditory and visual stimuli. Two used a bisection method, and two used verbal estimation. Auditory/visual differences were found when durations of auditory and visual stimuli were explicitly compared and when durations from both modalities were mixed in partition bisection. Differences in verbal estimation were also found both when people received a single modality and when they received both. In all cases, the auditory stimuli appeared longer than the visual stimuli, and the effect was greater at longer stimulus durations, consistent with a “pacemaker speed” interpretation of the effect. Results suggested that Penney, Gibbon, and Meck's (2000) “memory mixing” account of auditory/visual differences in duration judgements, while correct in some circumstances, was incomplete, and that in some cases people were basing their judgements on some preexisting temporal standard.     

When do auditory/visual differences in duration judgements occur?

Four experiments examined judgements of the duration of auditory and visual stimuli. Two used a bisection method, and two used verbal estimation. Auditory/visual differences were found when durations of auditory and visual stimuli were explicitly compared and when durations from both modalities were mixed in partition bisection. Differences in verbal estimation were also found both when people received a single modality and when they received both. In all cases, the auditory stimuli appeared longer than the visual stimuli, and the effect was greater at longer stimulus durations, consistent with a “pacemaker speed” interpretation of the effect. Results suggested that Penney, Gibbon, and Meck's (2000) “memory mixing” account of auditory/visual differences in duration judgements, while correct in some circumstances, was incomplete, and that in some cases people were basing their judgements on some preexisting temporal standard.     

When do visual and verbal memories conflict? The importance of working-memory load and retrieval

Examinations of interference between verbal and visual materials in working memory have produced mixed results. If there is a central form of storage (e.g., the focus of attention; N. Cowan, 2001), then cross-domain interference should be obtained. The authors examined this question with a visual-array comparison task (S. J. Luck & E. K. Vogel, 1997) combined with various verbal memory load conditions. Interference between tasks occurred if there was explicit retrieval of the verbal load during maintenance of a visual array. The effect was localized in the maintenance period of the visual task and was not the result of articulation per se. Interference also occurred when especially large silent verbal and visual loads were held concurrently. These results suggest central storage along with code-specific passive storage.     

How do people order stimuli?

People may find it easier to construct an order after first representing stimuli on a scale or categorizing them, particularly when the number of stimuli to be ordered is large or when some of them must be remembered. Five experiments tested this hypothesis. In two of these experiments (1 and 3), we asked participants to rank line lengths or to rank photographs by artistic value. The participants provided evidence of how they performed these tasks, and this evidence indicated that they often made use of some preliminary representation—either a metric or a categorization. Two further experiments (2 and 4) indicated that people rarely produced rankings when given a choice of assessment measures for either the length of lines or the artistic value of photographs. In Experiment 5, when the number of lines was larger or lines were only visible one at a time, participants were faster at estimating line lengths as a percentage of the card covered than at rank ordering the lengths. Overall, the results indicate that ordering stimuli is not an easy or natural process when the number of stimuli is large or when the stimuli are not all perceptible at once. An implication is that the psychological measures available to individuals are not likely to be purely ordinal when many of the elements being measured must be recalled.     

How much processing do nonattended stimuli receive? Apparently very little, but...

The early versus late selection issue in attention models was examined by means of a new methodology. Through cues or precues, attention was directed to one location of a multistimulus visual display and, while attention was so engaged, the identity of a stimulus located at a different position in the display was changed. By varying the time after display onset before the stimulus was changed, we controlled the preview time that the original stimulus was represented on the retina. Then, using a marker cue, we directed the subject's attention to the location of the changed stimulus. The subject's response was a timed discrimination between two possible target letters. The data of main interest was the effect of preview time upon the subject's latency in identifying the new target that appeared in the changed location. We found that the preview time of the original stimulus, before RT was affected to the new target, depended upon whether the original stimulus was a neutral (noise) letter or whether it was the alternative target. When the original stimulus was a noise letter, RTs to the new target were just as fast as those obtained in the control condition in which the target was present throughout the preview interval and did not change its identity. Significant effects upon RT were obtained at preview times of 83 msec when the original stimulus was one of the targets that changed to the alternative target. Preview times also varied as a function of precuing. Preview times were correspondingly shortened when the first cue occurred 50 msec before display onset, thus providing an extra 50 msec for attention to be directed to the first display location. The results were interpreted in terms of two separate information-processing systems in the human: an automatic system and an attentional system. Even though a stimulus may have been automatically processed, when the attention system is directed to that stimulus, processing starts at the beginning again.     

When do leotards get their spots? Semantic activation of lexical neighbors in visual word recognition

Shadowing and priming studies have provided strong evidence that during spoken word recognition, the meanings of different words that share their onset (e.g., captain and captive) are activated in parallel. In contrast, for visual word recognition, there is little evidence that the meanings of visually similar words are activated in parallel. This is consistent with the idea that for reading (in contrast to listening), since all the sensory information necessary to identify a word is available at once, any competition between visually similar words is resolved before their meanings are retrieved. However, Forster and Hector (2002) have recently shown that for nonwords (e.g., turple), some aspect of the meanings of lexical neighbors (e.g., turtle) can be activated. However, this finding is limited to non-words. The activation of turtle's meaning in response to turple may occur because turple has no meaning. In normal reading, we do not encounter nonwords, and there is strong pressure on the reading system to produce meaningful representations for every word (even misspelled words). The two semantic categorization experiments reported here extend this finding to real words. Participants are slower to decide that leotard is not an animal because of its animal neighbor leopard. This shows that information about a word's meaning can be available before it has been uniquely recognized.     

When does explicit justification impair decision making?

The idea that careful analysis leads to better decisions is pervasive in research on decision making. Intriguingly, results raise the possibility that thinking about reasons for decisions before deciding may degrade decision quality. This paper reports the results of a laboratory study which examined whether task characteristics critically influence the effects of thinking about reasons on decision quality. We found that explicit reasoning degraded judgement quality, objectively measured, on an ‘intuitive’ task. However, we also found that explicit reasoning enhanced performance on an ‘analytic’ task. Copyright © 2000 John Wiley & Sons, Ltd.     

When does action resist visual illusions?

Over the past decade, many studies of non-pathological individuals have reported functional dissociations between perceptual judgments and motor responses. These results suggested an interpretation of the ventral and dorsal streams in the primate visual system as independent modules for visual awareness and the visual guidance of actions. However, recent comparisons of perception and grasping responses in size-contrast displays have been widely reported to show that apparent dissociations are actually experimental artifacts. An overview of the literature suggests that the issue of visuomotor dissociations in healthy individuals is far from settled. Some results suggest that immunity from visual illusions might be found when task requirements emphasize observer-relative reference frames. These results suggest that the functional specialization of the two visual subsystems might be less rigid than originally posited.     

When can a lack of structure facilitate strategic processing of information?

Background: Researchers examining the effectiveness of an elaboration strategy (answering ‘why’) for learning new information have been concerned with the familiarity of the materials and how that affects learning. It may be, however, that both how information is organised and familiarity impact on the potency of the strategy. Aims: We examined the influence of presentation structures (i.e., organisation of information) on the effectiveness of an elaboration strategy. Samples: All participants were undergraduates (78 females, 67 males) enrolled in a first‐year psychology course. Fifteen students participated in Experiment One, 42 students in Experiment Two, and 88 students in Experiment Three. Methods: In Experiment One, preference for conceptual organisation was assessed. In Experiments Two and Three, students answered ‘why’ questions when different presentation structures were used. Results: Students' preferred method of organisation did not match the imposed structure found in past research, suggesting that students may have been restricted in their ability to process the information distinctively. Students who were presented with the information in a random order achieved the largest memory scores. Conclusions: When students have to reconstruct as well as encode the information, these added task demands provide an added benefit for learning.     

When does visual attention select all features of a distractor?

What happens after visual attention is allocated to an object? Although many theories of attention assume that all of its features are selected and processed, there has been little direct evidence that an irrelevant feature dimension of an attended nontarget is processed. In 5 experiments presented here, the authors used a singleton paradigm to investigate the effect of attention on nontarget objects. Participants made a speeded feature discrimination of a target for which the response was either compatible or incompatible with an irrelevant feature dimension of a distractor. The results show that the irrelevant distractor features were processed to the point that they interfered with the response to the target. The response compatibility effect was observed even when the location of the target or the distractor was invariant, although it was much weaker when both locations were invariant. These results demonstrate that in many circumstances, an attended distractor is completely selected and fully processed, and the complete processing of distractors depends on a number of factors, many of which are related to the strength of attention to the distractor.     

Preattentive face processing: What do visual search experiments with schematic faces tell us?

In recent research, several experiments have tested a preattentive threat-advantage hypothesis that threatening or negative faces can be discriminated preattentively, by using the visual search paradigm. However, supporting evidence is nonuniform, giving rise to the suspicion that stimulus factors rather than the stimuli's category of facial threat versus friendliness are responsible for sporadic demonstrations of a threat advantage. However, it is also possible that differences in experimental procedure contribute to the heterogeneous results. To test this possibility I selected examples from the past literature and presented them within the same constant experimental setting. I found a consistent advantage for negative face targets among positive face distractors with all stimulus pairs. Search slopes, however, mostly revealed inefficient search, questioning the preattentive discrimination of facial affect.