Perceptual learning without perception

Abstract

The brain is able to adapt rapidly and continually to the surrounding environment, becoming increasingly sensitive to important and frequently encountered stimuli. It is often claimed that this adaptive learning is highly task-specific, that is, we become more sensitive to the critical signals in the tasks we attend to. Here, we show a new type of perceptual learning, which occurs without attention, without awareness and without any task relevance. Subjects were repeatedly presented with a background motion signal so weak that its direction was not visible; the invisible motion was an irrelevant background to the central task that engaged the subject's attention. Despite being below the threshold of visibility and being irrelevant to the central task, the repetitive exposure improved performance specifically for the direction of the exposed motion when tested in a subsequent suprathreshold test. These results suggest that a frequently presented feature sensitizes the visual system merely owing to its frequency, not its relevance or salience.

Perceptual learning with perceptions

“…The results Watanabe et al (2001) obtained in their first test, before learning took place, indicate that there are two levels of coherent motion: One which leads to a performance of almost 0% and the other leads to a detection rate of about 50-60%. Figure 4 shows that similar results are obtainable for all three response thresholds evaluated, when using different values for the Watanabe et al (2001). Subjects were required to fixate a central cross (1°visual angle) and to judge whether coherent motion was present in the periphery (10°) or not.…”

“…Experimental setup Watanabe et al (2001) used slightly varying experimental setups to investigate the capability of perceptual learning when only subliminal and task irrelavant stimuli are presented to the subjects. The basic experimental setup is outlined in Fig.…”

“…Ball and Sekuler 1987;Vaina et al 1998), and that this ability might even increase without an actual perception (Watanabe et al 2001). Furthermore, neuroimaging studies demonstrated that changes in cortical activations might accompany perceptual learning in general (e.g.…”

“…within an Hebbian paradigm. In the following sections we outline the design of a neuronal model, capable to simulate the results obtained by Watanabe et al (2001) under this given constraints. Major parameters and underlying behavioral assumptions are explicated thus keeping the model design transparent.…”

“…Deco et al 2004;Stemme et al 2005Stemme et al , 2007Szabo et al 2006;Stemme and Deco 2008). To understand perceptual learning we focussed on the neurodynamical simulation of the ground breaking results presented by Watanabe et al (2001) who used subliminal stimuli for the (task irrelevant) training of participants. After training participants showed an increase in detection performance for these subliminal trained stimuli only, however, if they were presented above the perceptual threshold.…”