Object-Based Attention and Dual-Task Performance in Cognitive Processes

1. Cognitive ProcessesPSY 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.