Abstract
Load theory of attention stipulates that distinct attentional mechanisms underlie the effects of perceptual load, cognitive load, and sensory degradation on search performance. Such distinction mainly relies on the finding that increasing perceptual load reduces distractor interference whereas increasing sensory degradation or cognitive load magnifies distractor interference. We propose instead that all three manipulations simply highlight different aspects of task difficulty. We claim that the different patterns of results are due to the fact that increasing perceptual load has typically entailed the addition of neutral items capable of diluting distractor interference (Tsal & Benoni, 2010; Benoni & Tsal, 2010), whereas increasing sensory load and cognitive load has not. In the present series of experiments we jointly manipulated dilution with each type of load. We tested the effects of perceptual load, sensory degradation and memory load on distractor interference for three types of displays: low perceptual load, high perceptual load and dilution. The dilution displays contained neutral letters that were clearly distinguished from the target. Thus, these displays separated the effects of dilution and load by containing potential diluters, yet allowing for a low load processing mode. Similar results were obtained for the three types of load: when dilution was controlled, increasing task difficulty increased distractor interference, but the addition of potential diluters eliminated all types of distractor interference.
Israel Science Foundation.