PSY270H1 Lecture Notes - Lecture 4: Stroop Effect, Visual Search
Showed picture 1a then blank screen then picture 1b.
• Picture 1b: similar to picture 1a but changed object
• Can you determine what is different?
• Result: participants failed to initially detect the change from picture 1a to 1b – required
several viewings to detect change
Since attention is sometimes necessary for perception how do we function in daily life?
By focusing on one small portion of the environment our perceptual system is able to best
use our limited processing resources. In this way our inability to attend to all stimuli in the
environment is adaptive.
We do not need to be aware of all the details of what Is happening around us.
We can perceive some stimuli without paying close attention to them.
Spatial Attention:
Posner (1978) developed a precuing paradigm (images on slides)
3 types of trials:
Neutral- target location was not indicated
Valid- arrow directed attention to the correct location (80%)
Invalid- arrow directed attention to the incorrect location (20%)
(images on slides). It’s the cog lab we did.
Exogenous vs endogenous attention.
(Missed notes)
Selection Theories: spatial vs object based
Attention as a spotlight
An early metaphor for attention was that it was a spotlight that moved across space and lit the
attended location
Consistent with Posner’s findings - if attention was in the right location then processing was
faster than if it was in the wrong location
But does attention always need to be allocated to space or can it also be allocated to objects?
Egly, Driver, and Rafal (1994) tested object-based attention
▸Methods: Subjects saw 2 rectangles and a cue at the end of one rectangle (75% valid).
Responded to targets as quickly as possible
Invalid cues could either be in the same or different rectangle but distance was constant
▸Results: Faster for invalid trials in which the same object was cued
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PSY270H1 Full Course Notes
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Document Summary
By focusing on one small portion of the environment our perceptual system is able to best use our limited processing resources. In this way our inability to attend to all stimuli in the environment is adaptive. We do not need to be aware of all the details of what is happening around us. We can perceive some stimuli without paying close attention to them. Posner (1978) developed a precuing paradigm (images on slides) Valid- arrow directed attention to the correct location (80%) Invalid- arrow directed attention to the incorrect location (20%) (images on slides). An early metaphor for attention was that it was a spotlight that moved across space and lit the attended location. Consistent with posner"s findings - if attention was in the right location then processing was faster than if it was in the wrong location. Egly, driver, and rafal (1994) tested object-based attention.
