Early and Late Selection in Attention Flashcards
Early vs late selection in attention
First we process physical characteristics of stimuli (pitch and volume). Then we process this information semantically, but there is a bottleneck, so all information can’t be processed
The cocktail party effect
Ability to attend to some information and ignore the other
What does early selection believe?
That the bottleneck occurs early on the basis of physical characteristics
When we disregard, we only hear physical properties (tone) not semantic meaning
Broadbent’s filter theory
There is a filter which occurs before stimuli is analysed to the semantic level
Messages go to the sensory store (holds info) then to the filter (analyses message based on physical characteristics), then goes to the detector (processing meaning) and then goes into memory
Evidence of early selection theories
Dichotic listening task - Cherry
wear headphones, presented messages to each ear, subjects attended one ear, repeated message out loud (shadowing) and ignored other
results: attended message was easy, wasn’t demanding
unattended message - remembered physical characteristics but not much else, didn’t notice language change, reverse speech or if word was presented 35 times
Problems with early selection theories
Morary - dichotic listening task but presented name to unattended, they heard their name (own name breakthrough effect)
Triesman - bilinguals influenced by unattended stream if it is in their second language
Grey-weddeburn - left ear attended to: clear 7 Jane
right ear: 9 aunt 6. ppts said ‘dear aunt Jane’ - content from both streams processed - depends if it is meaningful
Triesman’s attentuation model
Modification to filter theory
Unattended messages are attenuated (reduced) rather than lost. Words need to meet a certain threshold of signal strength to be detected - threshold for some words lowered e.g. own name - has lots of meaning but some words need a higher level of sensory input for concept to be triggered e.g. non words
Explains the breakthrough of certain words
What does late selection mean?
Attentional selection occurs at a later point in the stream - selection occurs after meaning has been processed
Both attended and ignored processed to meaning
Selection takes place at higher stage of processing, based on which input is most important
Believes everything is processed to semantic stage, bottleneck occurs late when meaning has been extracted
What does late selection explain?
McKay - attended message was ambiguous sentence (throwing stones at bank; money or river?) Unattended was biasing word (river/money). the biased word influenced their interpretation e.g. if Monet, bank interpreted as financial
shows they processed unattended message
Response competition flanker task - report presence of a letter in presence of distractor letters. if early was correct, should be able to block out other letters based on physical characteristics so shouldn’t matter if distractor is congruent or incongruent. But, incongruent slows down Its, showing all distractors were processed
Negative priming- if asked to ignore something, responses slowed down. Task: categorise red, ignore green
Results - responses slowed down when preceded by semantically related ignored picture - suggests ignored stimuli is semantically categorised and inhibited
What theory believes both theories of selection are correct?
Lavie’s load theory - both are possible but whether it is early or late depends on availability of perceptual capacity which depends on the perceptual demands of task
Perceptual capacity is limited, high load tasks are demanding so exhaust capacity
irrelevant information is filtered out - early selection
lowland leaves spare capacity so irrelevant distractors are processed - late selection
Evidence of load theory
Response competition flanker task:
if low load - find response competition effects (incongruent slowing RT’s)
high load (search for target letter among lots of different letters, hard as process each one individual) - found no different if distractor was congruent or not - didn’t get processed
irrelevant distractor measure - put a picture on screen
if low load - distractors shows them down compared to no distractor
if high load, distractor has no effect
Inattentional blindness - failing to notice a gorilla because perceptually demanding task - capacity full
Cartwright finch and Lavie - 6 trials, unexpected stimulus
low load - 80% saw it, high load 40% saw it
Neuroimaging evidence for load theory
Task: low load - detect Red Cross
high load - detect conjunction (upside down yellow)
Ignore pattern in background (designed to create visual cortex activity)
high load reduces visual cortex visual cortex response to background - activity reduced early V1 - shows that they didn’t process pattern
Bishop et al - 2 types of load, shown fearful or neutral face in background
low load - increases amygdala response
high load - reduces response to fearful faces
Implications of load theory
Efficiency of attention depends on perceptual capacity - individual with high capacity need high load to avoid distraction
High capacity associated with: autism, age (children and elderly have reduced capacity) and video game experience
Video game players remained distracted under high load - effects found for autism, age and congenital deafness
