The Comparison of Visual Working Memory Representations With

Perceptual Inputs

Hyun, Woodman, Vogel, Hollingworth, & Luck

JEP: HPP 2009

• Changes can be detected by means of an unlimited-capacity comparison process, which can be used to direct covert and overt attention but that manual responses depend on a limited-capacity process.

• The unlimited-capacity comparison process can be limited to specificfeature dimensions.

Visual Working Memory (VWM)

• Working memory : A memory system that holds information temporarily so that it can be used in the service of some task.

• Visual Working Memory Representations & Perceptual Inputs

The Change Detection Task

• Commonly used to study the nature of the VWM representations.

1. form a perceptual representation→2. transformed into a stable working memory

representation →3. maintained across the retention interval →4. be compared with the sensory input →5. generate a single two-alternative response

Prior Research on Perceptual Comparison

• Taylor (1976)

A Theoretical Framework

• The change detection task can be considered a type of visual search task.

• three issues1. limited- or unlimited-capacity perceptual process2. presence of a feature & absence of a feature.3. voluntarily or involuntarily attracted

• three subhypotheses1. means of an unlimited capacity comparison process2. comparison asymmetry (search asymmetry effect)3. a shift of attention to the changed item (voluntary)

• key difference• the initial comparison process is unlimited in

capacity in two important ways

Experiment 1: Relating Change Detection to Perceptual Comparison

Experiment 2: Allocation of Covert Attention to the Changed Item

Experiment 3: Allocation of Overt Attention to the Changed Item

Experiments 4A and 4B: Effects of Set Size on Manual RTs

Experiment 5: Do Changes Attract Attention Involuntarily?

Overview of the Present Study

• RT increases much more steeply as a function of set size in the any-sameness task. (Exp1)

• The presence of a changed item in the test array in the any-difference task leads to a shift of attention to the location of this item. (Exp2&3)

Overview of the Present Study

• a limited-capacity process is interposed between the shift of attention and the observer’s button-press response. (Exp4A&4B)

• The shift of attention to a changed item is under voluntary control. (Exp5)

General Discussion

• Similarities Between Change Detection and Visual Search

• Limited- and Unlimited-Capacity Comparison Processes in Change Detection