Individual Differences in Visual Perceptual Processing: Attention, Intelligence, and Display Characteristics

Researchers have found little evidence that the ability to identify briefly presented simple stimuli (single letters, symbols) is related to intelligence in normal populations although performance on visual processing tasks which impose a greater attentional load (words, phrases, sentences) has been found to correlate with scores on reading tests. This study assessed the correlation between performance on seven visual processing tasks and intelligence as measured by the Raven's and the Nelson-Denny Reading Test. Intelligence correlated with tasks that required the identification of a confusable target, tasks in which the target was defined by a conjunction of features, and tasks in which the target was defined by its location. Intelligence did not correlate with the ability to identify single targets or targets defined by a single non-confusable feature. Other studies have shown that when attentional load is increased by increasing the number of characters in the display, performance is affected differently for confusable and conjunction targets. Increasing the attentional load reduces the number of hits in the confusable condition and increases the number of false alarms in the conjunction condition. In this study these two measures correlated with intelligence but not with each other, meaning that they assess different aspects of visual perceptual processing efficiency. We conclude that when it is critical to correctly identify targets and to avoid false alarms when monitoring complex displays, targets should not be confusable and should be defined by a single feature. When this is not possible, it is important to select operators who are more efficient at processing confusable and conjunction-defined stimuli.