Levels of noise processing and attentional control.

Abstract

Several studies in the recent literature have shown that subjects' ability to control their attention to specific objects in the visual field is limited in the sense that they are unable to completely gate out the processing of irrelevant and unwanted material. In the present study, the paradigm used by Posner and Mitchell was utilized to investigate levels of noise processing. Three experiments are reported in which subjects had to judge whether two letters were the same or different. Each experiment had different instructions for defining same responses-physical match, name-identity match, and category match for Experiments 1, 2, and 3, respectively. The two target letters were separated by 2.2° of visual angle, and two noise elements were inserted between them. The nature of the noise elements and their relation to the targets were experimentally varied and constituted the main focus of the present study. The results of all experiments were in complete agreement with those obtained by Posner and Mitchell, thus extending their conclusions to situations where noise is present. More important, the results suggest that noise elements are processed to the same level as targets. It was proposed that subjects are tuned by the nature of instructions to a certain level of processing (or by analogy, to a specific "program") and are unable to gate out-or process to a lower level-unwanted or irrelevant information near the targets. A final experiment demonstrated this conclusion is robust and holds even under situations where there is complete certainty with regard to the spatial position of the attended object.

Attentional distribution in the visual field duringsame-different judgments as assessed by response competition

“…On different trials, the noise letter was always response incompatible, since it was identical to one of the target letters. However, in this experiment, the performance on same trials was our primary diagnostic since the effect of incompatible noise on same judgments is more robust and sensitive (Farell, 1985;Keren et al, 1977).…”

“…James & C. W. Eriksen, 1991), the extent or two-dimensional shape of the attended area can be assessed by probing the visual field at different locations with response-incompatible noise stimuli. Keren et al (1977) were among the first to show that the RTs on same trials in a letter-matching task were appreciably increased if a nonmatching noise letter was presented in the display in an irrelevant location. C. W. have presented a response~ompetition interpretation of the effect and extended the research to show that RTs on different trials are increased if a nonrelevant noise letter that matches one of the target letters is present in the display (see also Garner, 1988).…”

“…It also permits us to determine whether there is a single circumscribed area that is attended or whether attention can be simultaneously concentrated on two separated locations in the visual field. The two forms constituting the target pair can be separated by varying distances in both the vertical and horizontal dimensions, and since same-different judgments have been shown to be quite sensitive to response-competition effects (C. W. Keren, O'Hara, & Skelton, 1977;Krueger, 1978;O'Hara, 1980;St. James & C. W. Eriksen, 1991), the extent or two-dimensional shape of the attended area can be assessed by probing the visual field at different locations with response-incompatible noise stimuli.…”

An electromyographic examination of response competition

“…W. Eriksen, B. A. Eriksen, & Hoffman, in press;Keren, O'Hara, & Skelton, 1977;Shaffer & LaBerge, 1979). B.…”

Indirect assessment of visual working memory for simple and complex objects

“…The speed to make the comparison (Figure 6) was equivalent between simple and complex objects [F(1,21) F F 1.9, p .17]. The lack of a difference cannot be attributed to a lack of statistical power; participants were significantly faster when the two objects were the same than when they were different, showing the well-known "fast-same" effect (Keren, O'Hara, & Skelton, 1977) [F(1,21) F F 9.2, p .01, with an observed power of 0.82].…”