Aubree Greenhalgh and Dr. Donovan Fleming, Psychology
Extensive research has been done with regards to attention and visual processing. Particular attention has been paid to preattentive processing which is the automatic registration of features by processing all targets simultaneously across the visual field (Matlin & Foley, 1997). Some of the particular properties which visual objects are composed of appear instantly and are, thus, processed faster (Treisman, 1985). In simpler terms, some targets are easier to recognize then others, especially if the targets differ greatly from their surroundings. For example, one square among many circles is easier to recognize then an oval or an octagon among a number of circles. The target seems to leap out from the display of the other objects without any effort from the observer, and for this reason, it is referred to as pop-out (Wang & Cavanagh, 1994). Accordingly, it is generally accepted that targets which differ from their surroundings are processed quicker then those that are similar. When the targets are similar to their surroundings, the observer has to visually search to recognize the difference; it is not as apparent.
It is proposed that memory is improved with preattentive processes. In dealing with preattentive memory, pop-out is an important factor. As stated above, the idea behind pop-out is that the brain is more attentive to targets that are easier to perceive, thus the targets “popout”. Accordingly, since pop-out is supposedly easier to recognize, memory should improve with such presentations. In order to test the effect of pop-out on memory, our study compared preattentive processes and visual search on a memory task. The study utilized different visual presentations to test if pop-out increases memory.
Thirty-three volunteer students from a Psychology 111 class were used as subjects. Each subject was put in a room and asked to sit in a comfortable chair placed approximately 24 inches away from a computer monitor. The monitor has in front of it a computer mouse, and both rest on a table. Each student was presented with the program instructions on the monitor. Each subject was presented with two different programs, one that tests pop-out (diamond as target) and one that tests visual search (left arrow as target). A coin was flipped to see which program is presented to the student first. The program presented a 3 row by 3 column matrix of right pointing arrows. The program randomly (50% of the time) put the target into the matrix.
The target, when presented, was randomly located in the matrix. 500msec before the matrix was presented to the subject, the program produced a 20msec. beep to signal to the subject that the matrix was about to be presented. After the matrix was displayed the subject responded by pressing the left mouse button if the target was in the matrix and the right mouse button if the target was not present. If the target was present, and the subject responded correctly by pushing the left mouse button, the program told the subject to wait. To test the effects on memory, there was a random (5 or 15 second) wait; then the program presented the mouse cursor on the monitor. The subject was instructed to place the cursor on the screen where the target was presented and press the left-mouse button. If the subject placed the cursor within the target area (50 mm. circle around the target) the program indicated on the screen a “HIT” or how close (mm.) they were. The subject was run on the program twice; once with the diamond as the pop-out, and again with a left pointing arrow as the visual search.
It was hypothesized that because the brain is more prone to perceive certain presentations, memory for pre-attentive processes should be better than visual search. Thus, the accuracy and number of hits is proposed to be better when the diamond as the pop-out is presented, rather than the left arrow as the visual search target. Unfortunately, our findings did not support this hypothesis. No significant difference between detection of the left-arrow and the diamond was found. In order to make sure the design was sound an unusually high number of subjects was used. It is believed that the task was too difficult and that the target area that would have resulted in a “Hit” was too small.
Subsequently, a new study is in process which is designed to test brain activity when a subject is presented with a pop-out and visual search task. Subjects are presented with a 3 by 3 or 5 by 5 matrix of left arrows and asked to identify a right arrow or diamond using the same method as listed above. Three electrodes are hooked up to three corresponding areas on the back of the head. These data are incomplete as yet. Accordingly, advances are currently being made in the field of psychology dealing with pop-out and visual search.
References
- Matlin, M., & Foley, H. (1997). Sensation and Perception. 4th ed. Boston: Allyn and Bacon.
- Treisman, A., & Gelade, G. (1980). A feature-integration theory of attention. Cognitive Psychology, 12, 97-136.
- Wang, Q., & Cavanagh P. (1994). Familiarity and pop-out in visual search. Perception & Psychophysics, 56, 495-500.