On the status of location in visual attention

The authors propose a distinction between four issues underlying the debate on the status of location in visual selective attention. Three of them concern the representation within which attention operates. The grouping question focuses on whether or not this representation segments the visual field into perceptual groups. The space-invariance question focuses on whether it describes objects in spatio-topic or in space-invariant coordinates. Finally, the feature-coding question concerns whether or not it contains information about objects' non-spatial features. The last issue focuses on whether or not attention can be guided preattentively towards items possessing certain pre-specified physical properties other than location, and is referred to as the attentional-guidance question. A critical survey of the literature within the proposed framework is presented. Based on its conclusions, the status of location in current research is outlined, and avenues for further research are suggested.     

Object-based selection under focused attention: a failure to replicate

In a recent study, Lavie and Driver (1996) reported that object-based effects found with distributed attention disappear when attention is focused on a narrow area of the display. This finding stands in contrast with previous reports of object-based effects under conditions of focused attention (e.g., Atchley & Kramer, 1998; Egly, Driver, & Rafal, 1994). The present study was an attempt to replicate Lavie and Driver's finding, using similar task and stimuli. While Lavie and Driver's object-based effect in the distributed attention condition was replicated, its absence in the focused attention condition was not. In the two experiments reported in this paper, object-based effects were found under conditions of both distributed and focused attention, with no difference in the magnitude of the object-based effects in the two conditions. It is concluded that, in contrast with Lavie and Driver's claim, the initial spatial setting of attention does not influence object-based constraints on the distribution of attention.     

Nature and nurture in own-race face processing

A standard visual preference task was used to examine 3-month-olds' looking times at own-race versus other-race faces as a function of environmental exposure to faces from the two categories. Participants were Caucasian infants living in a Caucasian environment, African infants living in an African environment, and African infants living in a predominantly Caucasian environment. The results indicate that preference for own-race faces is present as early as 3 months of age, but that this preference results from exposure to the prototypical facial environment.     

Attending to an object’s color entails Attending to its location: Support for location-special views of visual attention

Van der Heijden, Kurvink, de Lange, de Leeuw, and van der Geest (1996) argued that the results supporting the location-special view obtained by Tsal and Lavie (1988) were due to uncontrollable shifts of fixation, rather than reflecting the properties of the attentional system. In the present study, we present an improved variation of the Tsal and Lavie (1988) paradigm and reassert our claim that location is a special dimension. Subjects were presented with circular arrays of six letters of different colors. Three of the letters were enclosed by (Experiment 1) or superimposed on (Experiments 2,3, and 4) different colored shapes. The subjects were instructed to report the (target) shape with a given color (e.g., report whether the red shape was a square, a circle, or a triangle) and then either freely report letters from the array (Experiments 1, 2, and 4) or identify a prespecified target letter (Experiment 3). In all four experiments, performance was substantially better for the letter that appeared in the location of the to-be-reported shape (location letter) than for the letter that shared its color (color letter). We conclude that attending to the stimulus color entails directing attention to its location.     

Effects of search mode and intertrial priming on singleton search

There is no consensus as to what information guides search for a singleton target. Does the most salient display element capture attention, regardless of the observer's attentional set? Do observers adopt a default salience-based search mode? Does knowledge of the target's defining featural property (when available) affect search? Finally, can intertrial contingencies account for the disparate results in the literature? We investigated search for a shape singleton when (1) the target and nontarget shapes switched unpredictably from trial to trial, (2) the target feature remained fixed, and (3) the target was a singleton on only one third of the trials. We examined overall reaction times, search slopes, errors, and the magnitude of the slowing caused by a cross-dimensional singleton distractor. Our results argue against the idea that search is guided solely by stimulus-driven factors or that subjects adopt a singleton detection mode that is blind to feature information. They show also that intertrial contingencies, although potent, cannot account for the variety of results in the literature.     

Threat-related attentional bias in anxious and nonanxious individuals: a meta-analytic study

This meta-analysis of 172 studies (N = 2,263 anxious,N = 1,768 nonanxious) examined the boundary conditions of threat-related attentional biases in anxiety. Overall, the results show that the bias is reliably demonstrated with different experimental paradigms and under a variety of experimental conditions, but that it is only an effect size of d = 0.45. Although processes requiring conscious perception of threat contribute to the bias, a significant bias is also observed with stimuli outside awareness. The bias is of comparable magnitude across different types of anxious populations (individuals with different clinical disorders, high-anxious nonclinical individuals, anxious children and adults) and is not observed in nonanxious individuals. Empirical and clinical implications as well as future directions for research are discussed.     

The role of within-dimension singleton priming in visual search

The authors report a newly identified intertrial priming phenomenon, within-dimension singleton priming, by which search for a target that happens to be a singleton on the current trial is faster when the target on the previous trial had also been a singleton on the same dimension rather than a nonsingleton. This effect was replicated in 6 experiments with different procedures, with singletons on various dimensions, when the featural contrast defining the singleton remained the same or changed within a dimension from one trial to the next, and when the target was a singleton on a target-defining dimension or on an irrelevant dimension. These findings cannot be explained by previously demonstrated intertrial repetition effects such as dimension-specific priming or priming of pop-out. Theoretical implications of the within-dimension singleton priming phenomenon are discussed relative to the dimension-weighting hypothesis, the role of stimulus-driven salience in feature-guided search, and the roles of intertrial priming and goal-directed factors in visual search.     

Unconscious auditory information can prime visual word processing: a process-dissociation procedure study

Whether information perceived without awareness can affect overt performance, and whether such effects can cross sensory modalities, remains a matter of debate. Whereas influence of unconscious visual information on auditory perception has been documented, the reverse influence has not been reported. In addition, previous reports of unconscious cross-modal priming relied on procedures in which contamination of conscious processes could not be ruled out. We present the first report of unconscious cross-modal priming when the unaware prime is auditory and the test stimulus is visual. We used the process-dissociation procedure [Debner, J. A., & Jacoby, L. L. (1994). Unconscious perception: Attention, awareness and control. Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 304-317] which allowed us to assess the separate contributions of conscious and unconscious perception of a degraded prime (either seen or heard) to performance on a visual fragment-completion task. Unconscious cross-modal priming (auditory prime, visual fragment) was significant and of a magnitude similar to that of unconscious within-modality priming (visual prime, visual fragment). We conclude that cross-modal integration, at least between visual and auditory information, is more symmetrical than previously shown, and does not require conscious mediation.     

The effect of fixation point on the appearance of rectilinearity

Data from two experiments indicate that (a) within 3.5 deg visual angle of the fixation point, an eccentrically fixated line and dot appear rectilinear when they are objectively convex toward the fixation point; (b) beyond 3.5 deg, they appear rectilinear when they are objectively concave; (c) the latter effect is not an artifact of the use of stationary fixation points; and (d) the addition of an extraneous line to the stimulus line so as to form a 90-deg angle acts as if to reduce the apparent size of the angle, but does not alter fixation point effects. The data were interpreted as supporting (a) the hypothesis that the stimulus line was more sensitive to illusory distortion than the dot, and (b) the ID (increasing-decreasing) model of the visual field—an inner area of increasing concentric contraction (stimuli appear to lie nearer the fixation point to a degree which increases with distance from the fixation point) is bounded by an outer area of decreasing concentric contraction.     

The P3 component of the ERP reflects conscious perception, not confidence

Consistent with numerous electrophysiological studies, we recently reported that conscious perception is associated with a widely distributed modulation of the P3 component (Lamy, Salti, & Bar-Haim, 2009). We also showed that correct objective performance in the absence of subjective awareness is associated with a spatially more restricted modulation of the P3. The relatively late occurrence of the P3 along with lack of control for post-perceptual processes suggests that this component might reflect processes related to stimulus evaluation or confidence rather than to visual awareness or objective performance. The main aim of the current study was to test this hypothesis. While EEG was recorded, participants performed a forced-choice localization task and reported their subjective perception of the target on a 3-level scale that also indexed their confidence. The results showed that our previous findings are replicated when confidence is controlled for.