Lecture 3 Flashcards
Define attention
The selection of task- relevant information
Can be sensory information from the environment of internal information
Does selective attention act as a filter?
Yes
What is used to decide what the stimuli are and how to respond to them?
Attentional resource
What do filter theories argue?
That attention prevent the processing of irrelevant stimuli
What do resource theories argue?
That attention permits the selection of appropriate responses
What do both filter theories and resource theories assume?
The capacity of a resource or filter is limited.
Attention capacity limits
Attention capacity is limited to 3-4 items
Sperling partial report- participants report 3-4 items
In some cases it is limited to 1 item
Multiple object tracking (Pylyshym and Storm)
Participants can accurately track up to 5 objects
Only works with objects- collections of features which are not obkects cannot be tracked in this way
What is the debate over capacity limits?
Some debate over the number of locations that can be attended to:
Some say multiple loci (up to 4)
Others argue single
Where does the attentional bottleneck occur?
Filter and Resource theories
Filter theories place the bottleneck early in processing : attention operates at the level of sensory analysis, unattended stimuli are not processed semantically
Resource: place botlleneck late in processing
All inputs get processed at semantic leel, attention operates at level of response selection
Broadbent evidence for early selection
Argued that unfiltered stimuli are not processed
Shadowing- poor recall for information presented to unattended ear
Selecting looking
Change blindness
Inattentional blindness
Attentional blink
Processing of unfiltered stimuli evidence for early selection
Breakthrough - occasionally words from unattended ear reported
Attenuated filter as evidence for early selection
Irrelevant information can pass through filter if capacity not filled by relevant information
Sensory processing
Attention affects produces signal enhancement:
Attention enhances spatial resolution ]Attended locations have higher perceived contrast
Evidence from neurophysiology:
Attention modulates the responses of early visual areas such as V1, V2, V4 & V5
Attention lowers phosphene thresholds in V1
Evidence for late selection
Number of paradigms which appear to show late selection.
Can occur when meaning of distracting stimuli is processed
+Flanker Effects
+Stroop effects
+Negative priming
Can also occur when responses must be selected sequentially
+Psychological refractory period (PRP)
Electrophysiology: Hillyard
Electrophysiological studies of auditory attention
Participants attend to one ear, ignore the other
Detect occasional probe stimuli
N1 reflects enhanced early processing of stimuli presented to attended ear- this enhanced processing applied to both standards and targets
p300 reflects late enhancement of processing probe sound. Reflects the late selection or targets
Can attention modulate both early and late processing?
Yes
Perceptual load theory
Perceptual load= how hard it is to process the perceptual featurees of display
+Low load - all items in a display pass through the filter and get analysed
+Irrelevant items interfere with processing of relevant ones
+High load - only task relevant items pass through the filter
+Irrelevant items cannot interfere with processing of relevant stimuli
Lavie
Propose a passive limited capacity filter and an active central resources:
+Filter used to process the perceptual properties of stimuli
+Central resource used for identification and decision making
Neurophysical evidence
Perceptual load modules activity of early visual areas
Rees
+Low load - words in lower/upper case
+High load - how many syllables
Irrelevant - motion fields in background
Muggleton
+Perform letter ID task
+TMS delivered over MT/V5
+Higher intensity TMS required during high load
