Cognitive Processes PSY 334

1. Cognitive ProcessesPSY 334 Chapter 3 – Attention July 8, 2003

2. What is Attention? • Attention is the allocation of limited processing resources. • Visual features such as shape, color, texture, motion are processed in parallel. • Serial bottleneck – occurs when it is no longer possible to process in parallel. • When does it occur – early vs late selection • How do we select what to attend to?

3. How we Experience Attention • Stream of consciousness -- we learn and remember what we attend to. • Paying attention results in a feeling of mental effort. • Can be directed internally but also pulled (attracted) by external events. • Varies with arousal and fatigue. • Studied by looking at response competition.

4. Auditory Attention • The response competition comes from having two ears. • Dichotic listening task – uses “shadowing.” • Two different messages are presented, one to each ear. Subjects are asked to speak what they hear. • People can attend to only one message at a time.

5. Three Theories • Broadbent’s filter theory • Treisman’s attenuation theory • Deutsch & Deutsch’s late selection theory

6. Broadbent’s Filter Theory • People do not remember the content of the unattended ear. • Voice or noise, sex, but little else. • Broadbent’s filter theory proposed that filtering occurs early in processing based on physical characteristics (pitch, ear). • Neural evidence supports the ability to select one ear to listen to. • Cocktail party effect – attention switches based on content of unattended ear.

7. Treisman’s Attenuation Theory • Treisman’s attenuation theory – subjects deemphasize but not filter out the unattended message. • Meaning switched from one ear to the other. • Some subjects switch ears even when told not to, following the semantic content. • Semantic criteria apply to all messages, filtered or not.

8. Late Selection Theory • Deutsch & Deutsch’s late selection theory – the limitation is in the response system, not the perception. • Both messages are perceived but only one can be shadowed at a time. • The criterion for selecting what to say can change – based on ear or meaning.

9. Testing the Theories • Dichotic listening task: • Shadow one message but listen for a target word in both ears (tap when heard). • Late selection theory predicts no difficulty hearing the target in either ear. • Attenuation theory predicts less detection in non-shadowed ear. • 87% detection in shadowed ear • 8% detection in non-shadowed ear

10. Echoic Memory • Glucksberg & Cowen demonstrated that unattended information can be kept in an echoic memory buffer for brief periods. • Shadow a message, with digit presented to non-shadowed ear. • 25% of time, is asked immediately after presentation, reported hearing the digit. • 5% of time reported the digit, without cuing • Unattended material is lost within 5 seconds.

11. Visual Attention • We can choose where to fixate our eyes for greatest visual acuity. • Other portions of the visual field are attenuated. • Visual attention need not be located where the eyes are fixed. • Posner – subjects can attend to objects up to 24 degrees from the fovea. • Shift of attention precedes eye movement.

12. Spotlight Metaphor • Spotlight can be broad or narrow (degrees of visual angle). • Broad areas processed less well. • A narrow focal point gives optimal processing but it takes time to move the focus to other areas of the visual field. • We move our eyes around a complex visual stimulus. • Neisser & Becklen’s shadowing task.

13. Neural Basis of Attention • Attention consists of enhanced neural response in a particular area of the brain. • The brain is organized topographically. • By increasing neural activity in a particular location, input to that location can be processed faster. • Specific details are “higher order” properties and take longer to recognize.

14. Iconic Memory • Visual sensory input can be remembered for a short time – up to 5 seconds. • Retention time varies if a post-exposure field is light (1 sec) vs dark (5 sec). • Following one display with another display “washes out” the first memory (icon). • Visual sensory information must be attended to and processed in order to be remembered longer.

15. Sperling’s Partial Report • The purpose of an icon is to retain an image until attention can focus upon it. • How long does the icon last? • How fast can attention move through it? • Subjects see an array of letters flashed briefly (50 ms), then report them back. • After the array is gone, a tone is sounded. • Subjects must report the letters in the row corresponding to the tone (high, med, low).