Perceptual learning transfers to untrained retinal locations after double training: A piggyback effect

Modulating temporal dynamics of performance across retinotopic locations enhances the generalization of perceptual learning

Human visual perception can be improved through perceptual learning. However, such learning is often specific to stimulus and learning conditions. Here, we explored how temporal dynamics of performance across conditions impact learning generalization. Participants performed a visual task, with the target at retinotopic location A. Then, the target was presented at location B either immediately after location A (same-session performance) or following a 48h consolidation period (different-session performance). Long-term generalization was measured the following week. Following initial training, both groups demonstrated generalization, consistent with previous accounts of fast learning. However, long-term generalization was enhanced in the same-session performance group. Consistently, improvements at locations A and B were correlated only following same-session performance, implying an integrated learning process across locations. The results support a new account of perceptual learning and generalization dynamics, suggesting that the temporal proximity of learning and consolidation of different conditions may integrate correlated learning processes, facilitating generalized learning.

Current directions in visual perceptual learning

The visual expertise of adult humans is jointly determined by evolution, visual development, and visual perceptual learning. Perceptual learning refers to performance improvements in perceptual tasks after practice or training in the task. It occurs in almost all visual tasks, ranging from simple feature detection to complex scene analysis. In this Review, we focus on key behavioral aspects of visual perceptual learning. We begin by describing visual perceptual learning tasks and manipulations that influence the magnitude of learning, and then discuss specificity of learning. Next, we present theories and computational models of learning and specificity. We then review applications of visual perceptual learning in visual rehabilitation. Finally, we summarize the general principles of visual perceptual learning, discuss the tension between plasticity and stability, and conclude with new research directions.

Training with an auditory perceptual learning game transfers to speech in competition

Understanding speech in the presence of acoustical competition is a major complaint of those with hearing difficulties. Here, a novel perceptual learning game was tested for its effectiveness in reducing difficulties with hearing speech in competition. The game was designed to train a mixture of auditory processing skills thought to underlie speech in competition, such as spectral-temporal processing, sound localization, and auditory working memory. Training on these skills occurred both in quiet and in competition with noise. Thirty college-aged participants without any known hearing difficulties were assigned either to this mixed-training condition or an active control consisting of frequency discrimination training within the same gamified setting. To assess training effectiveness, tests of speech in competition (primary outcome), as well as basic supra-threshold auditory processing and cognitive processing abilities (secondary outcomes) were administered before and after training. Results suggest modest improvements on speech in competition tests in the mixed-training compared to the frequency-discrimination control condition (Cohen’s d = 0.68). While the sample is small, and in normally hearing individuals, these data suggest promise of future study in populations with hearing difficulties.

Vernier learning with short- and long-staircase training and its transfer to a new location with double training

We previously demonstrated that perceptual learning of Vernier discrimination, when paired with orientation learning at the same retinal location, can transfer completely to untrained locations (Wang, Zhang, Klein, Levi, & Yu, 2014; Zhang, Wang, Klein, Levi, & Yu, 2011). However, Hung and Seitz (2014) reported that the transfer is possible only when Vernier is trained with short staircases, but not with very long staircases. Here we ran two experiments to examine Hung and Seitz's conclusions. The first experiment confirmed the transfer effects with short-staircase Vernier training in both our study and Hung and Seitz's. The second experiment revealed that long-staircase training only produced very fast learning at the beginning of the pretraining session, but with no further learning afterward. Moreover, the learning and transfer effects differed insignificantly with a small effect size, making it difficult to support Hung and Seitz's claim that learning with long-staircase training cannot transfer to an untrained retinal location.

Limited transfer of visual skill in orientation discrimination to locations treated by pre-testing and subliminal exposure

Substantial transfer of perceptual skill learning can be achieved across large distances in the visual field by a brief pre-test, training-plus-exposure, or a double-training paradigm (Xiao et al., 2008; Zhang, Xiao, et al., 2010; Zhang, Zhang, et al., 2010). Additionally, subliminal exposure has been shown to be beneficial for subsequent perceptual learning. Here, we tested the generalization of orientation discrimination learning from a fully trained location towards four other test locations, either in the same or opposite hemifield as the training location, which each were subjected to a different type of pre-conditioning. In one test location, there was brief pre-testing in the first session. Two other locations were stimulated by masked stimuli similar or identical to concurrently presented stimuli in the training location. In the fourth test location, no stimuli were presented during training. Generalization of training to test locations was measured in the session immediately following the completion of training in the training location. Moreover, to test the robustness of transfer, training was continued in all four test locations. The experiment as a whole consisted of 15 sessions of orientation discrimination learning at the training location, followed by 15 sessions of training in the test locations. We found only limited generalization from the trained to the test locations. Performance in pre-tested and stimulated test locations showed a small advantage compared to the unstimulated test location. However, this advantage disappeared within a few sessions of further training in the test locations.