Short-term perceptual learning in visual conjunction search.

Abstract

Although some studies showed that training can improve the ability of cross-dimension conjunction search, less is known about the underlying mechanism. Specifically, it remains unclear whether training of visual conjunction search can successfully bind different features of separated dimensions into a new function unit at early stages of visual processing. In the present study, we utilized stimulus specificity and generalization to provide a new approach to investigate the mechanisms underlying perceptual learning (PL) in visual conjunction search. Five experiments consistently showed that after 40 to 50 min of training of color-shape/orientation conjunction search, the ability to search for a certain conjunction target improved significantly and the learning effects did not transfer to a new target that differed from the trained target in both color and shape/orientation features. However, the learning effects were not strictly specific. In color-shape conjunction search, although the learning effect could not transfer to a same-shape different-color target, it almost completely transferred to a same-color different-shape target. In color-orientation conjunction search, the learning effect partly transferred to a new target that shared same color or same orientation with the trained target. Moreover, the sum of transfer effects for the same color target and the same orientation target in color-orientation conjunction search was algebraically equivalent to the learning effect for trained target, showing an additive transfer effect. The different transfer patterns in color-shape and color-orientation conjunction search learning might reflect the different complexity and discriminability between feature dimensions. These results suggested a feature-based attention enhancement mechanism rather than a unitization mechanism underlying the short-term PL of color-shape/orientation conjunction search.

Stored color–form knowledge modulates perceptual sensitivity in search

“…A somewhat contrasting view has come from Su et al (2014). These authors examined the effect of training on conjunction search.…”

“…In the Frank et al (2014) study, observers learned over the course of eight sessions over eight days. Su et al (2014) tested observers in one experimental session lasting 40-50 min. Thus, it might be that the mechanisms underlying efficient conjunction search and the deployment of object-based attention dynamically change over the course of learning and depend on the robustness and quality of feature associations and object representations (Chen, 2012).…”

Brain mechanisms underlying behavioral specificity and generalization of short-term texture discrimination learning

“…In addition, some behavioral studies found that visual PL depends on perceptual constancy (Garrigan & Kellman, 2008) and is diagonal mirror-transferable (Chen et al, 2008). Accordingly, it was also proposed that visual PL occurs at the middle visual stages, such as the extrastriate cortex including V2-V4, where neurons are characterized by both orientation/location selectivity and more complex properties (Chen et al, 2008), and involves feature-based selective attention (Su et al, 2014). Several brain imaging studies have directly investigated the brain mechanisms of specificity and generalization of human visual PL (e.g., Ding et al, 2003;Schiltz et al, 1999;Song et al, 2007).…”

Perceptual learning induces active suppression of physically nonsalient shapes

“…Detectability relies on not only physical properties of the stimulus (e.g., physical salience) but also observers’ prior experience (e.g., learning history). For example, previous studies reported that detectability of a stimulus could be enhanced through perceptual learning (Su et al, ; Watanabe, Náñez, & Sasaki, ). In Qu et al’s study (), although subjects’ performance improved through training, the final accuracy ( p’ ) of detecting a trained triangle in a visual display was only 0.345, which was far less than detecting a feature singleton (e.g., Girelli & Luck, ), indicating that the detectability of a trained triangle was very low even after extensive training.…”