Top-down versus bottom-up attentional control: a failed theoretical dichotomy

Prominent models of attentional control assert a dichotomy between top-down and bottom-up control, with the former determined by current selection goals and the latter determined by physical salience. This theoretical dichotomy, however, fails to explain a growing number of cases in which neither current goals nor physical salience can account for strong selection biases. For example, equally salient stimuli associated with reward can capture attention, even when this contradicts current selection goals. Thus, although 'top-down' sources of bias are sometimes defined as those that are not due to physical salience, this conception conflates distinct--and sometimes contradictory--sources of selection bias. We describe an alternative framework, in which past selection history is integrated with current goals and physical salience to shape an integrated priority map.     

Updating the premotor theory: The allocation of attention is not always accompanied by saccade preparation

There is an ongoing controversy regarding the relationship between covert attention and saccadic eye movements. While there is quite some evidence that the preparation of a saccade is obligatory preceded by a shift of covert attention, the reverse is not clear: Is allocation of attention always accompanied by saccade preparation? Recently, a shifting and maintenance account was proposed suggesting that shifting and maintenance components of covert attention differ in their relation to the oculomotor system. Specifically, it was argued that a shift of covert attention is always accompanied by activation of the oculomotor program, while maintaining covert attention at a location can be accompanied either by activation or suppression of oculomotor program, depending on the probability of executing an eye movement to the attended location. In the present study we tested whether there is such an obligatory coupling between shifting of attention and saccade preparation and how quickly saccade preparation gets suppressed. The results showed that attention shifting was always accompanied by saccade preparation whenever covert attention had to be shifted during visual search, as well as in response to exogenous or endogenous cues. However, for the endogenous cues the saccade program to the attended location was suppressed very soon after the attention shift was completed. The current findings support the shifting and maintenance account and indicate that the premotor theory needs to be updated to include a shifting and maintenance component for the cases in which covert shifts of attention are made without the intention to execute a saccade. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

The time course of attentional bias to cues of threat and safety

It is well known that relative to neutral stimuli, attention is biased towards processing stimuli that convey threat. In a previous study in which a particular stimulus (e.g. a blue diamond) was associated with the delivery of an electrical shock, the presence of the fear-conditioned stimulus interfered with the execution of voluntary eye movements to other locations. Here, we show that this effect not only occurs early in time, but remains present long after the fear-conditioned stimulus was removed from the screen. In a subsequent experiment, we associated the presence of a particular stimulus with safety, that is, when this stimulus was present it was certain that no electrical shock would be delivered. The presence of the safety signalling stimulus also interfered with the execution of voluntary saccades, but only when the time between stimulus and cue presentation was relatively long. The results indicate that both signals of threat and signals of safety interfere with execution of a saccade long after the source of threat or safety has been removed. However, only threatening stimuli affect saccade execution early in time, suggesting that threatening stimuli drive selection exogenously.     

The factor structure of the Eysenck Personality Profiler in Russia

One hundred and seventy seven males and 399 females completed a translated short version of the Eysenck Personality Profiler (EPP-S). Two hundred and ninety four Ss also completed the EPQ. By means of item analysis, further shortening of the EPP was achieved, while retaining adequate psychometric characteristics and convergent validity with EPQ scales. Confirmatory factor analysis (CFA) confirmed the Eysenck hierarchical model of personality with three basic dimensions and showed stability of the EPP factor structure across genders and sub-samples of different origin. However, CFA showed that only E and P were independent, while N was correlated with E and P.     

The role of fear and expectancies in capture of covert attention by spiders

Fear-related stimuli are often prioritized during visual selection but it remains unclear whether capture by salient objects is more likely to occur when individuals fear those objects. In this study, participants with high and low fear of spiders searched for a circle while on some trials a completely irrelevant fear-related (spider) or neutral distractor (butterfly/leaf) was presented simultaneously in the display. Our results show that when you fear spiders and you are not sure whether a spider is going to be present, then any salient distractor (i.e., a butterfly) grabs your attention, suggesting that mere expectation of a spider triggered compulsory monitoring of all irrelevant stimuli. However, neutral stimuli did not grab attention when high spider fearful people knew that a spider could not be present during a block of trials, treating the neutral stimuli just as the low spider fearful people do. Our results show that people that fear spiders inspect potential spider-containing locations in a compulsory fashion even though directing attention to this location is completely irrelevant for the task. Reduction of capture can only be accomplished when people that fear spiders do not expect a spider to be present.     

Detecting the presence of a singleton involves focal attention

It has been claimed that the detection of a feature singleton can be based on activity in a feature map that allows coarse coding that something unique is present in the visual field. In the present study, participants detected the presence or absence of a color singleton. Even though the letter form of the color singleton was task-irrelevant, we showed that repeating the letter form of the singleton resulted in repetition priming on the next trial. Such repetition priming was not found when a nonsingleton letter was repeated as the singleton. Since the letter form of the color singleton could only be picked up by focal attention, the repetition priming effect indicates that focal attention is allocated to the feature singleton even in the simplest present-absent feature detection tasks. We showed that this effect is equally strong in conditions of low and high perceptual load. These results are inconsistent with theories that it is possible to detect a feature singleton without directing some form of attention to its location.     

When Are Attention and Saccade Preparation Dissociated?

ABSTRACT— To understand the mechanisms of visual attention, it is crucial to know the relationship between attention and saccades. Some theories propose a close relationship, whereas others view the attention and saccade systems as completely independent. One possible way to resolve this controversy is to distinguish between the maintenance and shifting of attention. The present study used a novel paradigm that allowed simultaneous measurement of attentional allocation and saccade preparation. Saccades toward the location where attention was maintained were either facilitated or suppressed depending on the probability of making a saccade to that location and the match between the attended location and the saccade location on the previous trial. Shifting attention to another location was always associated with saccade facilitation. The findings provide a new view, demonstrating that the maintenance of attention and shifting of attention differ in their relationship to the oculomotor system.     

The limits of top-down control of visual attention

The extent to which spatial selection is driven by the goals of the observer and by the properties of the environment is one of the major issues in the field of visual attention. Here we review recent experimental evidence from behavioral and eye movement studies suggesting that top-down control has temporal and spatial limits. More specifically, we argue that the first feedforward sweep of information is bottom-up, and that top-down control can influence selection only after the sweep is completed. In addition, top-down control can limit spatial selection through adjusting the size of attentional window, an area of visual space which receives priority in information sampling. Finally, we discuss the evidence found using brain imaging techniques for top-down control in an attempt to reconcile it with behavioral findings. We conclude by discussing theoretical implications of these results for the current models of visual selection.     

Dynamic presentation of magnified graphical characters on the IBM-compatible computers

Software that provides extremely smooth gliding and scrolling of magnified characters and pictograms on standard PCs is described. The program was designed as a tool for reading research, as a computer aid for visually impaired readers, and as a subtitle generator for multimedia applications. Change of font, size of characters, speed, color, and direction of movement can be made interactively. The system is useful for reading remediation and for creation of various visual effects.