Perceptual load theory of attention

Perceptual load theory (Lavie, 1995)

• Can explain the contradictory early and late selection findings
• sometimes selection is late and sometimes it is early - it depends on the perceptual load
• Perceptual load refers to the amount of perceptual processing that has to be undertaken
• The theory retains the early selection notion that perceptual systems can't process all the information available to the fullest extent
• and that attention is the means of selecting a subset of the information available for detailed processing
• if processing of information selected is not perceptually demanding, then spare processing capacity is unintentionally and automatically allocated to other available information

High perceptual load - many resources are used for a perceptually demanding task and thus few are available to process ignored inputs

Low perceptual load - few resources are used to a perceptually non-demanding task and thus many are available to process ignored inputs

Neuroimaging research - high perceptual load reduces or eliminates neural activity related to distractor perception

 

Some criticisms of the PLT

- Perceptual load is what perceptual load tests test, there is no clear refutation for perceptual load

- Dilution effects - many experiments manipulate load by varying the number of items in the display. Low load conditions tend to have few distractors whereas high load conditions tend to have multiple distractors. The interference from one specific distractor may be diluted by the presence of the other distractors

 

The efficiency of selective attention is dependent not only on perceptual load but also on cognitive load

 

Load theory of Selective attention and Cognitive control

• Lavie (2004, 2010) theorised that executive functions are necessary are attentional selection under low p-load conditions
• We use executive control to inhibit distractor stimuli
• We can vary the availability of executive processes (and therefore out inability to inhibit distractors) by manipulating cognitive load

An alternative view

• Some evidence indicates that cognitive load in fact reduces susceptibility to distraction
• Sorqvist and Marsh (2015) propose that cognitive load shields against distraction by a. reducing undesired processing of distractors and b, enhancing events/stimuli within the focus of attention