The attentional blink: Resource depletion or temporary loss of control?

Identification of the second of two targets is impaired if it is presented less than about 500 ms after the first. Theoretical accounts of this second-target deficit, known as attentional blink (AB), have relied on some form of limited attentional resource that is allocated to the leading target at the expense of the trailing target. Three experiments in the present study reveal a failure of resource-limitation accounts to explain why the AB is absent when the targets consist of a stream of three items belonging to the same category (e.g., letters or digits). The AB is reinstated, however, if an item from a different category is inserted in the target string. This result, and all major results in the AB literature, is explained by the hypothesis that the AB arises from a temporary loss of control over the prevailing attentional set. This lapse in control renders the observer vulnerable to an exogenously-triggered switch in attentional set.     

Object updating and the flash-lag effect

Flash lag is a misperception of spatial relations between a moving object and a briefly flashed stationary one. This study began with the observation that the illusion occurs when the moving object continues following the flash, but is eliminated if the object's motion path ends with the flash. The data show that disrupting the continuity of the moving object, via a transient change in size or color, also eliminates the illusion. We propose that this is because a large feature change leads to the formation of a second object representation. Direct evidence for this proposal is provided by the results for a corollary perceptual feature of the disruption in object continuity: the perception of two objects, rather than only one, on the motion path.     

Mislocalizations of touch to a fake hand

Observers can mislocalize a tactile target delivered to an unseen hand if a visible rubber glove is positioned next to a pair of distractor lights that flash in correlation with the tactile target (Pavani, Spence, & Driver, 2000). In the present study, we explored visual, tactile, and postural factors that influence this fake hand effect. Comparison with baseline conditions revealed that the fake hand effect was larger than a general spatial congruity effect but weaker than the effect obtained when tactile and visual stimuli were actually in the same locations (Experiment 1). Surprisingly, the effect did not depend on direct vision of the fake hand (Experiments 1 and 2), nor was it enhanced by congruent tactile information (Experiment 3). However, the fake hand effect was sensitive to the postural compatibility of the real and the fake hands (Experiment 4). These findings indicate that the available sensory information is used flexibly to incorporate the rubber glove into the body schema.     

Target detection and localization in visual search: a dual systems perspective

The dual visual systems framework (Milner & Goodale, 1995) was used to explore target detection and localization in visual search. Observers searched for a small patch of tilted bars against a dense background of upright bars. Target detection was performed along with two different localization tasks: direct pointing, designed to engage the dorsal stream, and indirect pointing, designed to engage the ventral stream. The results indicated that (1) target detection was influenced more by orientation differences in 3-D space than by 2-D pictorial differences, (2) target localization was more accurate for direct than for indirect pointing, and (3) there were performance costs for indirect localization when it followed target detection, but not for direct localization. This is consistent with direct localization's having greater dependence on the dorsal visual system than either target detection or indirect localization.     

Visual masking plays two roles in the attentional blink

When two targets are displayed in rapid visual sequence and masked by trailing patterns, identification accuracy is nearly perfect for the first target but follows a U-shaped pattern over temporal lag for the second target. Three experiments examined the role of visual masking in this attentional blink. Experiment 1 compared integration and interruption masks for both targets. Although either mask was effective in producing the blink when applied to the first target, only the interruption mask was effective when applied to the second target. Experiment 2 showed that integration masking of the second target was ineffective over a wide range of accuracy levels. Combining the two forms of masking in Experiment 3 confirmed the dissociation: A combined mask and only a main effect on accuracy for the first target, whereas it produced a qualitatively different pattern over temporal lag for the second target. These results suggest that representations of the target are substituted in consciousness by that of the interruption mask when visual attention is preoccupied.     

VSearch Color: Full-color visual search experiments on the Macintosh II

We describe an update to our visual search software for the Macintosh line of computers. The new software, VSearch Color, gives users access to the full-color capabilites of the Macintosh II line. One of the key features of the new software is its ability to treat graphics information separately from color information. This makes it easy to study color independently of form, to design experiments based on isoluminant stimuli, and to incorporate texture segregation, visual identification, number discrimination, adaptation, masking, and spatial cuing into the basic visual search paradigm.     

Self-Report Differentiation of Anxiety and Depression in a Mood Disorders Sample

Several lines of research suggest there is considerable overlap between anxiety and depression and that it is difficult to distinguish between these two constructs. However, a few studies utilizing factor analytic procedures have provided evidence that anxiety and depression can be differentiated when measures of these constructs are considered at the item level. In addition, there is some evidence that differentiation can be accomplished in samples experiencing high levels of anxiety (i.e., a clinically anxious sample; B. J. Cox, R. P. Swinson, L. Kuch, & J. Reichman, 1993). In the present study, this research strategy was extended to a sample of patients with high levels of depressed mood (i.e., a mood disorders sample; N = 378). Their responses to widely used measures of depression (i.e., Beck Depression Inventory; A. T. Beck, C. H. Ward, M. Mendelson, J. Mock, & J. Erbaugh, 1961) and anxiety (i.e., Spielberger State-Trait Anxiety Inventory—State subscale; C. D. Spielberger, R. L. Gorsuch, & R. E. Lushene, 1970) were entered into a principal-components analysis with oblique rotation. A 4-factor solution was retained. This solution was comprised of factors representing anxiety, anxiety absent (a reverse scored factor), cognitive symptoms of depression, and somatic/vegetative symptoms of depression. These findings indicated that anxiety and depression, as emotional states, can be differentiated within a mood disorders sample, using existing popular self-report measures. The clinical and research implications of these findings are briefly discussed.     

New objects dominate luminance transients in setting attentional priority.

Both the sudden appearance of an object and sudden changes in existing object features influence priority in visual search. However, direct comparisons of these influences have not been made under controlled conditions. In 5 visual search experiments, new object onsets were compared directly with changes in the luminance of old objects. Factors included the luminance contrast of items against the background, the magnitude of luminance change, and the probability that these changes were associated with the target item. New objects were consistently more effective in guiding search, such that a new item with very low luminance contrast was equivalent to an old item undergoing a large change in luminance. An important exception was an old item changing in contrast and polarity, which was as effective as the appearance of a new object. This indicates that search priority is biased toward object rather than situational changes.     

Confirmatory Factor Analysis of the Depression–Anxiety–Stress Scales in Depressed and Anxious Patients

The Depression–Anxiety–Stress Scales (DASS; P. F. Lovibond & S. H. Lovibond, 1995) have shown considerable promise in their ability to differentially assess depression and anxiety symptoms. Most of the work to date has relied on normal or predominantly anxious clinical samples. To extend this research to a predominantly depressed sample, a psychiatric sample from a mood disorders program (N = 439) was used to investigate the factor structure of the DASS. Confirmatory factor analyses indicated that a 3-factor model for the 21-item DASS was supported. A 3-factor model with crossloading items for the 42-item version showed no practical improvement. Further confirmatory analyses evaluated the ability of item subsets from the DASS to represent the constructs specified in the tripartite model (L. A. Clark & D. Watson, 1991). Strong support was obtained for the DASS to represent the construct of anhedonia and physiological hyperarousal, and their relative importance is consistent with predictions of the tripartite model in understanding the relationship between anxiety and depression.     

In sight, out of mind: the role of eye movements in the rapid resumption of visual search

Three experiments investigated the role of eye movements in the rapid resumption of an interrupted search. Passive monitoring of eye position in Experiment 1 showed that rapid resumption was associated with a short distance between the eye and the target on the next-to-last look before target detection. Experiments 2 and 3 used two different methods for presenting the target to the point of eye fixation on some trials. If eye position alone is predictive, rapid resumption should increase when the target is near fixation. The results showed that gaze-contingent targets increased overall search success, but that the proportion of rapid responses decreased dramatically. We conclude that rather than depending on a high-quality single look at a search target, rapid resumption of search depends on two glances; a first glance in which a hypothesis is formed, and a second glance in which the hypothesis is confirmed.