Inhibition and attention control in a cued target and flanker paradigm

The idea that inhibition is functionally important for visual processing is not new. Research has demonstrated inhibitory mechanisms in visual attention through visual search, inhibition of return, negative priming, novel pop-out, and visual marking. Previous research in our lab has demonstrated that previous knowledge about upcoming flankers decreases the time to locate a central target. This research has relied on a small set of target and flanker combinations, which could be grouped into a perceptual unit. If grouping occurs positive priming could explain these effects with no reliance on an inhibitory mechanism. Experiment I increased the number of target/flanker combinations thereby, decreasing the probability of grouping. Faster response times for correct target identification were still found when participants were provided cues to the upcoming flanker.; Two explanations could account for the results of experiment 1. Activation of the flanker, which is then ignored when the test display is presented, or active suppression of the flanker items. Experiment 2 attempted to differentiate these two possibilities. Both target and flanker cues were provided with some probability. Expectations regarding the cue validity were established based on these probabilities, Presented cues conformed with or violated these expectations. Results indicated participants reliably used expected target cues to facilitate target identification, but flanker cues impaired target identification when target cues were expected. Expected flanker cues did not facilitate target identification, and target cues did not facilitate target identification. An expectancy bias was found for cues in which participant responded to no cue expectancy as if it provided target cue information. This may have diminished expected effects in the expected flanker cue condition.; A neural network model was provided. The model used lateral and top-down inhibition to simulate flanker incompatibility effects, negative priming, and the current cued target and flanker experiments. The model was successful in simulating target/flanker compatibility effects, as well as offering a new explanation of negative priming. The model also simulated the effects of the current experiment, and offered simulated effects of the cueing effect on negative priming.; Both the experiments and model support an inhibition explanation of the cued flanker effect. However, experimental bias and possible asymmetry of inhibitory effects on flanker suppression and target interference may constrain the usefulness of these effects in practical terms. However, they do provide convincing evidence of the importance of inhibition in visual selective attention.