Attentional capture and aging: implications for visual search performance and oculomotor control

Two studies examined potential age-related differences in attentional capture. Subjects were instructed to move their eyes as quickly as possible to a color singleton target and to identify a small letter located inside it. On half the trials, a new stimulus (i.e., a sudden onset) appeared simultaneously with the presentation of the color singleton target. The onset was always a task-irrelevant distractor. Response times were lengthened, for both young and old adults, whenever an onset distractor appeared, despite the fact that subjects reported being unaware of the appearance of the abrupt onset. Eye scan strategies were also disrupted by the appearance of the onset distractors. On about 40% of the trials on which an onset appeared, subjects made an eye movement to the task-irrelevant onset before moving their eyes to the target. Fixations close to the onset were brief, suggesting parallel programming of a reflexive eye movement to the onset and goal-directed eye movement to the target. Results are discussed in terms of age-related sparing of the attentional and oculomotor processes that underlie attentional capture.     

Confidence in judgments based on incomplete information: An investigation using both hypothetical and real gambles

This study assessed how confidence in judgments is affected by the need to make inferences about missing information. Subjects indicated their likelihood of taking each of a series of gambles based on both probability and payoff information or only one of these sources of information. They also rated their confidence in each likelihood judgment. Subjects in the Explicit Inference condition were asked to explicitly estimate the values of missing information before making their responses while subjects in the Implicit Inference condition were not. The manner in which probability information was framed was also manipulated. Experiment 1 employed hypothetical gambles and Experiment 2 employed gambles with real money. Expressed likelihood of taking gambles was higher when probability was phrased in terms of '% chance of winning' rather than '% chance of losing', but this difference was somewhat less with real gambles than with hypothetical gambles. Confidence ratings in each experiment were actually higher on incomplete information trials than on complete information trials in the Explicit Inference condition. Results were related to the general issue of confidence in judgments.     

The locus of spatial attention during the temporal integration of visual memories and visual percepts

Temporal integration is a process by which two serially presented visual stimuli are mentally integrated to form a composite representation. In the present research, we explored how spatial selective attention is used during the delay separating stimuli, in order to determine the contents of spatial working memory in this task. A two-task situation was created. On the primary task, two dot arrays were serially presented within a grid, leaving one space empty, which subjects identified. On the secondary task, instead of the second array, a discrimination probe was presented. Integration accuracy increased through delays of 1,500 msec, revealing an estimate of the time required to form an optimal memory trace for integration. Once the memory trace was formed (but not before), response time to the probe was faster if it was presented in a location previously occupied by a dot from Array 1. This indicates that during the delay separating the arrays, the subjects assigned spatial attention to the locations occupied by the first array and actively maintained the leading array in working memory. Implications for theories of visual processing and memory are discussed.     

Order effects in belief updating with consistent and inconsistent evidence

The current study tests for the presence of differential order effects in evaluation tasks with consistent and inconsistent evidence as predicted by the Hogarth and Einhorn (1992) belief-adjustment model. The results, based on both between-subjects and within-subjects experiments, demonstrate that there were significant recency effects with inconsistent evidence as predicted, larger recency effects when the inconsistent evidence was farther apart in subjective value as predicted, and significant recency effects even when subjects were given training designed to both help them understand the task as completely as possible and to be better able to assess the pieces of evidence. By including a within-subjects design, we were able to demonstrate that the difference in subjective value between two pieces of evidence is the primary factor influencing the magnitude of the recency effect, regardless of whether the evidence is consistent or inconsistent. This latter finding is unique and contrary to previous research and theory.     

Invariance of the weight parameter in information integration

The relative effect of each informational dimension in an information integration task is a joint function of its weight and the range of values over which it is varied. A method is developed for separating these two factors. Weights obtained by this method were compared across variations of stimulus range. Subjects rated the performance of students on the basis of midterm exam scores and final exam scores. For some subjects, the range of scores on the final exam was twice that on the midterm and the reverse was true for other subjects. An averaging model was shown to describe the results, and weights did not differ for different stimulus ranges. This was true for each of two instructional conditions: one in which a particular weighting strategy was prescribed and one in which there was no prescribed weighting. Students who were instructed to use a 2∶1 weighting were found to assign more than twice as much weight to the final as to the midterm.     

Where does attention go when you blink?

Many studies have shown that covert visual attention precedes saccadic eye movements to locations in space. The present research investigated whether the allocation of attention is similarly affected by eye blinks. Subjects completed a partial-report task under blink and no-blink conditions. Experiment 1 showed that blinking facilitated report of the bottom row of the stimulus array: Accuracy for the bottom row increased and mislocation errors decreased under blink, as compared with no-blink, conditions, indicating that blinking influenced the allocation of visual attention. Experiment 2 showed that this was true even when subjects were biased to attend elsewhere. These results indicate that attention moves downward before a blink in an involuntary fashion. The eyes also move downward during blinks, so attention may precede blink-induced eye movements just as it precedes saccades and other types of eye movements.