PSYC 213 Chapter Notes - Chapter 4: Inattentional Blindness, Nystagmus, Stroop Effect
28 May 2018
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Chapter 4: Varieties of Attention
James' Description of Attention
• William James leading psychologist in 1900s in North America
o Book: Principles of Psychology
o Describes attention as "taking possession by the mind … of one of what seem several
simultaneously possible objects or trains of through"
• There are many types/variations of attention --complex concept
• Pashler: states that no one knows what attention is
Selective Attention
• Early research centered around problem with communication in armed forces where many
different streams of speech reached person at same time
• Dichotic listening: participants presented two verbal messages at the same time (i.e. one in
each ear) and asked to attend only one of them
o Then asked questions about what heard
o Broadbent
• Performance very good when told which message would be asked questions about
o Selective attention: able to select relevant information form stimuli and ignore the rest
• Cocktail party phenomenon: able to attend one conversation in crowded room in which many
conversations going on
o Cherry
• Shadow task: participants wear headphones, given two different messages (on per ear) and
asked to shadow one of the messages by repeating it as they hear it
• Theories suggest that attention relies on a filter that lets some messages pass through and
block others
• Selective looking: participant exposed to two visual events at the same time, but attend only
one of them
o Shown two different videos overlapping --people able to attend either one well while not
being distracted by the other
o Neisser & Becklen
Theories of Attention
• Both dichotic listening & selective looking studies showed results supporting the early selection
view of attention; suggests that attention prevents early perceptual processing of irrelevant
information
o Participants thus do not see or hear information from distractor
• Other studies more consistent with late selection view of attention; both relevant & irrelevant
information is perceived, and participant must actively ignore distractor
o Supported by Stroop task
Stroop Task
• Show words of colours' names written in a specific color (i.e. green, red, purple)
• Much harder (longer) to name the color that see rather than what is written
o Must focus, deliberately inhibit tendency to read (overlearned)
o Slower naming / performance in incongruent condition
• Variant in which shown picture of one animal labelled with name of another animal
• Controlled process: requires attention to be carried out properly
o Top-down, voluntary, goal-directed
• Automatic processes: operates without requiring us to pay attention
o Bottom-up, involuntary, stimulus-driven
• Raz: participants who scored high on the Stanford Hypnotic Susceptibility Scale test did the
Stroop test after being told post-hypnosis that the words were in a foreign language or to not
attribute meaning to them
o Highly suggestible participants did not show the Stroop effect whereas those less
suggestible did
o Reading of the word suppressed
o Automatic process like reading can be controlled by hypnosis
• Implies that automatic processes are subject to top-down influences exerted by suggestion at
neural level
• Brain imaging studies showed that dorsolateral prefrontal cortex and anterior cingulate
cortex were often active during Stroop test
o Both activated during tasks eliciting competing responses
o dLPFC exert top-down bias favoring selection of task-relevant information
o ACC detects conflicting response tendencies (monitor performance)
• Activity associated with heightened awareness of conflicts
• Part of attentional network, can have different function depending on task
Endogenous & Exogenous Spatial Attention
• Spatial attention: process of selecting visual information in specific region of space for
conscious awareness
o Like a spotlight shining onto objects in certain location (spotlight metaphor)
• Spatial information can be moved in 2 ways:
o Shifting attention does not refer to eye movements but rather shift in focus
• Endogenous shifts: volitional/voluntary, determined by goals & intentions
• Exogenous shifts: involuntary, determined by external stimuli that grabs our attention
regardless of goals & intentions
o Attention capture: diversion of attention by powerful stimulus that compels us to notice
it even when attention directed towards something else
o Ecologically useful --i.e. shift attention to threat (avoid) or opportunity (prey)
Exogenous Shifts Testing
• Central cueing paradigm: central cue (arrow) points in location in which target might
subsequently occur
o Central fixation point replaced with directional cue, which reliably predicts target location
(i.e. 80% of time)
• Participant intentionally shifts attention (strategically)
o Response time faster when target presented in cued location
o No IOR present for long intervals (inhibition of return)
• Can lead to cueing effects when non-predictive of target location
o Arrows can shift attention in a reflexive manner
Exogenous Shifts Testing
• Demonstrated using peripheral cueing paradigm: test in which flashing light in periphery (cue)
is followed by target either in cued or uncued location
o Participant fixating cross in center of screen
o Asked to press button as soon as target appears
o Some trials have no target presented to discourage random button pressing (catch
trials)
o 1/2 time shown in cued location and 1/2 in uncued; attending cue does not help
maximize performance
o Participants faster at detecting target when appears in cued location
• Cue captures attention; no need to shift when appears in cued
• Called cueing effect
• Shift in attention is involuntary
• Stimulus onset asynchrony (SOA) is the time interval between cue and target onset
o Do same experiment but varying this interval
1. Cueing effect present at very short SOA (25ms)
o Peripheral cues attract attention very rapidly
2. Cueing effect diminishes as interval increases, and reverses at long SOA (1200ms)
o As time interval increases, initially pay attention to the light flash, but when no target
appears then attention disengages and shifts to uncued location
• At 200 ms, detection starts to be faster at the uncued location
• Response time increases
o Inhibition of return (IOR) = reversed cueing effect for long intervals
• Endogenous shifts are slower & voluntary whereas exogenous shifts are ballistic (rapid) &
reflexive
o Also seems to be faster & have larger difference with uncued for endogenous cues
(arrows)
Attention Capture vs. Inattentional Blindness
• Inattentional blindness: failure to attend events that we are expected to notice
o Opposite to attention capture
o i.e. someone behind you says your name and you don't hear and don't turn around as
expected
o Or pilot landing plane focusing on monitors while failing to notice other plane blocking
runway
• Simons: overlapping videos of two teams playing basketball, asked participants to count
passes made by one of the teams
o 73% failed to notice gorilla walking across screen
o 50% failed to notice when stopped and pounded its chest
• Mack & Rock: participants shown series of asymmetrical crosses and asked to judge which
arm of the cross was longer
o Many failed to perceive the black square in top corner that appeared in fourth trial
• Used to find what types of stimuli capture attention
o If replace black square with happy cartoon face, gets detected 85% of time
