1. Cognitive Processes PSY 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).