Abstract
Purpose. Most of the studies on the characteristics of visual short-term memory (VSTM) used somewhat familiar stimuli, such as simple visual attributes (e.g., color, orientation), entry-level objects, faces, or natural scenes. However, with these types of visual material, it is difficult to completely rule out the influence of individual subject's prior knowledge or familiarity with the stimuli. Therefore, the goal of the present study was to explore the nature of VSTM for unfamiliar, abstract patterns spreading on a 5*5 checker board.
Methods. We used Corel Draw (v.11) to generate the stimuli, and E-Prime 2.0 to run the experiments. The subjects sat at a viewing distance of 57 cm with a chin rest. Each trial began with a fixation cross, then an abstract pattern (made of 12 or 13 red squares) within the 5*5 checkers appeared for a fixed duration, and a probe X located in one of the four quadrants appeared. The subjects‘ task was to judge whether the square in which the X located overlapped with the red pattern or not. Experiment 1 investigated the effects of overall pattern symmetry (asymmetrical v.s. symmetrical), element connectedness (high v.s. low), and probe quadrant (upper-left, upper-right, lower-left, and lower-right). Experiment 2 further explored the effects of the stimulus sizes, in which three sizes were used (20°×21°, 13°×14°, 6.8°×7.2°).
Results. Based on error rate data, results of Experiment 1 showed significant effects of element connectedness, symmetry, and quadrant of probe, indicating that memory for abstract pattern was more accurate when the pattern was symmetrical, had a higher connectedness, and easier to recall for probes located in the upper-left quadrant. Results of Experiment 2 showed a mild size effect, where more errors occurred with larger stimulus size. Further data collection is in progress.
This project was supported by Grant# NSC 97-2410-H-039-006 to Dr. Sarina H. L. Chien.