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Spatial probability AIDS visual stimulus discrimination.

Druker M, Anderson B - Front Hum Neurosci (2010)

Bottom Line: Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search.This produced fewer spatial repeats and allowed us to dissociate the effect of a high-probability location from that of short-term spatial repetition.These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Waterloo Waterloo, ON, Canada.

ABSTRACT
We investigated whether the statistical predictability of a target's location would influence how quickly and accurately it was classified. Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search. One explanation for probability cuing is spatial repetition priming. In our two experiments we used probability distributions that were continuous across the display rather than relying on a few arbitrary screen locations. This produced fewer spatial repeats and allowed us to dissociate the effect of a high-probability location from that of short-term spatial repetition. The task required participants to quickly judge the color of a single dot presented on a computer screen. In Experiment 1, targets were more probable in an off-center hotspot of high-probability that gradually declined to a background rate. Targets garnered faster responses if they were near earlier target locations (priming) and if they were near the high-probability hotspot (probability cuing). In Experiment 2, target locations were chosen on three concentric circles around fixation. One circle contained 80% of targets. The value of this ring distribution is that it allowed for a spatially restricted high-probability zone in which sequentially repeated trials were not likely to be physically close. Participant performance was sensitive to the high-probability circle in addition to the expected effects of eccentricity and the distance to recent targets. These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect. Future models of attention should consider explicitly incorporating the probabilities of targets locations and features.

No MeSH data available.


Related in: MedlinePlus

Stimuli in Experiment 2 were located in concentric circles at 3°, 6°, and 9° of visual angle from fixation, with one circle containing 80% of stimuli and the other two containing 10% each. Plotted here is the full set of stimulus locations for one participant in the middle-heavy condition. Five centimeters near fixation subtended just over 4° of visual angle.
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Figure 2: Stimuli in Experiment 2 were located in concentric circles at 3°, 6°, and 9° of visual angle from fixation, with one circle containing 80% of stimuli and the other two containing 10% each. Plotted here is the full set of stimulus locations for one participant in the middle-heavy condition. Five centimeters near fixation subtended just over 4° of visual angle.

Mentions: The key difference between Experiments 1 and 2 was the probability distribution used for target locations. In Experiment 2 the locations of targets were fixed to one of three distances from the center of the screen (3°, 6°, or 9° of visual angle). For each participant targets fell at one of these distances from the center of the screen and the radial direction from the center of the screen was chosen uniformly from 0 to 2π. The result was that target locations were distributed into three concentric circles (see Figure 2). Each participant was assigned to one of three probability conditions that specified which of the three radial distances was most likely to be chosen for the target location. There were 12 participants in the inner-heavy, 19 in the middle-heavy, and 12 in the outer-heavy conditions. The designation “heavy” means that that radial distance was chosen 80% of the time while the other two distances were equally probable at 10%.


Spatial probability AIDS visual stimulus discrimination.

Druker M, Anderson B - Front Hum Neurosci (2010)

Stimuli in Experiment 2 were located in concentric circles at 3°, 6°, and 9° of visual angle from fixation, with one circle containing 80% of stimuli and the other two containing 10% each. Plotted here is the full set of stimulus locations for one participant in the middle-heavy condition. Five centimeters near fixation subtended just over 4° of visual angle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927278&req=5

Figure 2: Stimuli in Experiment 2 were located in concentric circles at 3°, 6°, and 9° of visual angle from fixation, with one circle containing 80% of stimuli and the other two containing 10% each. Plotted here is the full set of stimulus locations for one participant in the middle-heavy condition. Five centimeters near fixation subtended just over 4° of visual angle.
Mentions: The key difference between Experiments 1 and 2 was the probability distribution used for target locations. In Experiment 2 the locations of targets were fixed to one of three distances from the center of the screen (3°, 6°, or 9° of visual angle). For each participant targets fell at one of these distances from the center of the screen and the radial direction from the center of the screen was chosen uniformly from 0 to 2π. The result was that target locations were distributed into three concentric circles (see Figure 2). Each participant was assigned to one of three probability conditions that specified which of the three radial distances was most likely to be chosen for the target location. There were 12 participants in the inner-heavy, 19 in the middle-heavy, and 12 in the outer-heavy conditions. The designation “heavy” means that that radial distance was chosen 80% of the time while the other two distances were equally probable at 10%.

Bottom Line: Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search.This produced fewer spatial repeats and allowed us to dissociate the effect of a high-probability location from that of short-term spatial repetition.These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Waterloo Waterloo, ON, Canada.

ABSTRACT
We investigated whether the statistical predictability of a target's location would influence how quickly and accurately it was classified. Recent results have suggested that spatial probability can be a cue for the allocation of attention in visual search. One explanation for probability cuing is spatial repetition priming. In our two experiments we used probability distributions that were continuous across the display rather than relying on a few arbitrary screen locations. This produced fewer spatial repeats and allowed us to dissociate the effect of a high-probability location from that of short-term spatial repetition. The task required participants to quickly judge the color of a single dot presented on a computer screen. In Experiment 1, targets were more probable in an off-center hotspot of high-probability that gradually declined to a background rate. Targets garnered faster responses if they were near earlier target locations (priming) and if they were near the high-probability hotspot (probability cuing). In Experiment 2, target locations were chosen on three concentric circles around fixation. One circle contained 80% of targets. The value of this ring distribution is that it allowed for a spatially restricted high-probability zone in which sequentially repeated trials were not likely to be physically close. Participant performance was sensitive to the high-probability circle in addition to the expected effects of eccentricity and the distance to recent targets. These two experiments suggest that inhomogeneities in spatial probability can be learned and used by participants on-line and without prompting as an aid for visual stimulus discrimination and that spatial repetition priming is not a sufficient explanation for this effect. Future models of attention should consider explicitly incorporating the probabilities of targets locations and features.

No MeSH data available.


Related in: MedlinePlus