1. Cognitive Processes PSY 334
Chapter 3 – Attention
April 18, 2003

2. Object-Based Attention
Attention can be focused on particular objects, not just regions of space.
Sometimes it is easier to attend to an object (bumps on stimuli).
Inhibition of return – if we have already looked at a location it is harder to return to it.
Flickering squares take longer to identify because already viewed, even when rotated.

3. A Central Bottleneck
We can only process one thing at a time within a single modality (vision, hearing).
What happens when we combine modalities?
Dual-task studies
How does stimulus onset asynchrony (SOA) affect performance of the second task?
If the two tasks can be done in parallel there should be no effect of SOA.

4. Dual-Task Performance
The first task must be completed before the second task can be done.
There is some time gained by overlapping the tasks.
The stimulus is encoded while doing the other task – two modalities can be processed at once.
The bottleneck occurs at the thinking – the subject cannot think about both tasks at once.

5. Automaticity
Practice reduces the demand on cognition by making a task automatic.
Spelke’s two tasks:
Read text for comprehension
Write down words read by an experimenter
After 6 weeks subjects could read at normal speed and answer questions.

6. Stroop Effect
Color words were presented printed in different ink colors.
Control stimuli were non-color words in different inks or color bars (not words)
Subjects were asked to name the ink color as quickly as possible.
Demo

7. Why it Happens Automatic processes are difficult to stop.
It is nearly impossible to look at a word without reading it.
Neutral words name non-colors so ink can be named without interference.
Color words that conflict with ink color take longer because reading the word cannot be inhibited.

8. Practice With Stroop Tasks
What happens if you compare tasks that are not well-practiced?
MacCleod & Dunbar asked subjects to associate color names with shapes.

9. MacCleod & Dunbar’s Conditions
Congruent – random shape was in the same ink color as its name.
Control –
white shapes were presented and subjects said the name of the color for that shape
colored shapes were presented and subjects named the ink color of the shape
Conflict – the random shape was in a different ink color than its name.

10. Results
At first, color naming was more automatic than shape naming and was unaffected by congruence with shape.
After 20 days practice, shape naming was affected by congruence with ink color
Practice reversed the Stroop effect and made shape naming like color naming.

11. Current Views of Attention
Theorists no longer associate attention with consciousness.
Many attentional phenomena (such as moving one’s eyes) are unconscious.
Each modality has its own attentive processes and a bottleneck when it must process a single thing.
Interference occurs with competing demands on a single system.