Journal of Experimental Psychology: Human Perception and Performance Volume 26, Issue 1, 2000

Perceptual learning in clear displays optimizes perceptual expertise: Learning the limiting process
Barbara Anne Dosher , and Zhong-Lin Lu
Memory, Attention, and Perception (MAP) Laboratory, Department of Cognitive Sciences and Institute of Mathematical Behavioral Sciences, University of California, Irvine, CA 92697-5100; and Laboratory of Brain Processes (LOBES), Departments of Psychology and Biomedical Engineering and Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089-1061
Communicated by Richard M. Shiffrin, Indiana University, Bloomington, IN, February 24, 2005 (received for review August 25, 2004)

Abstract


Human operators develop expertise in perceptual tasks by practice or perceptual learning. For noisy displays, practice improves performance by learned external-noise filtering. For clear displays, practice improves performance by improved amplification or enhancement of the stimulus. Can these two mechanisms of perceptual improvement be trained separately? In an orientation task, we found that training with clear displays generalized to performance in noisy displays, but we did not find the reverse to be true. In noisy displays, the noise in the stimulus limits performance. In clear displays, performance is limited by noisiness of internal representations and processes. Our results suggest that training in one display condition optimizes the limiting factor(s) in performance in that condition and that noise filtering is also improved by exposure to the stimulus in clear displays. The asymmetric pattern of transfer implies the existence of two independent mechanisms of perceptual learning, which may reflect channel reweighting in adult visual system. These results also suggest that training operators with clear stimuli may suffice to improve performance in a range of clear and noisy environments by simultaneous learning by two mechanisms

DVD Santa

Independent perceptual learning in monocular and binocular motion systems
Abstract

Top Abstract Materials and Methods Results Summary and Discussion Appendix References

Eye-transfer tests, external noise manipulations, and observer models were used to systematically characterize learning mechanisms in judging motion direction of moving objects in visual periphery (Experiment 1) and fovea (Experiment 2) and to investigate the degree of transfer of the learning mechanisms from trained to untrained eyes. Perceptual learning in one eye was measured over 10 practice sessions. Subsequent learning in the untrained eye was assessed in five transfer sessions. We characterized the magnitude of transfer of each learning mechanism to the untrained eye by separately analyzing the magnitude of subsequent learning in low and high external noise conditions. In both experiments, we found that learning in the trained eye reduced contrast thresholds uniformly across all of the external noise levels: 47 � 10% and 62 � 8% in experiments 1 and 2, respectively. Two mechanisms, stimulus enhancement and template retuning, accounted for the observed performance improvements. The degree of transfer to the untrained eye depended on the amount of external noise added to the signal stimuli: In high external noise conditions, learning transferred completely to the untrained eye in both experiments. In low external noise conditions, there was only partial transfer of learning: 63% in experiment 1 and 54% in experiment 2. The results suggest that template retuning, which is effective in high external noise conditions, is mostly binocular, whereas stimulus enhancement, which is effective in low external noise displays, is largely monocular. The two independent mechanisms underlie perceptual learning of motion direction identification in monocular and binocular motion systems.

perceptual learning

GILBERT, C. D. Early perceptual learning. Proc. Natl. Acad. Sci. USA 91: 1195-1197, 1994.

Perceptual Learning of Spatial Localization: Specificity for Orientation, Position, and Context
Roy E. Crist, Mitesh K. Kapadia, Gerald Westheimer, and Charles D. Gilbert
Department of Neurobiology, The Rockefeller University, New York, New York 10021

ABSTRACT

Abstract Introduction Methods Results Discussion References
Crist, Roy E., Mitesh K. Kapadia, Gerald Westheimer, and Charles D. Gilbert. Perceptual learning of spatial localization: specificity for orientation, position, and context. J. Neurophysiol. 78: 2889-2894, 1997. Discrimination of simple visual attributes can improve significantly with practice. We have trained human observers to perform peripherally presented tasks involving the localization of short line segments and examined the specificity of the learning for the visual location, orientation, and geometric arrangement of the trained stimulus. Several weeks of training resulted in dramatic threshold reductions. The learning was specific for the orientation and location of the trained stimulus, indicating the involvement of the earliest cortical stages in the visual pathway where the orientation and location of stimuli are mapped with highest resolution. Furthermore, improvement was also specific for both the configuration of the trained stimulus and the attribute of the stimulus that was under scrutiny during training. This degree of specificity suggests that the learning cannot be achieved by cortical recruitment alone, as proposed in current models, but is likely to involve a refinement of lateral interactions within the cortex and possibly a gating of lower level changes by attentional mechanisms.

Practising orientation identification improves orientation coding in V1 neurons
ANIEK SCHOUPS*, RUFIN VOGELS*, NING QIAN� & GUY ORBAN*
* Laboratorium voor Neuro-en Psychofysiologie, K.U. Leuven Medical School, B-3000 Leuven, Belgium
� Center for Neurobiology and Behavior, and Department of Physiology and Cellular Biophysics, Columbia University, New York 10032, USA

Correspondence and requests for materials should be addressed to A.S. (e-mail: annick.schoups@med.kuleuven.ac.be).
The adult brain shows remarkable plasticity, as demonstrated by the improvement in fine sensorial discriminations after intensive practice. The behavioural aspects of such perceptual learning are well documented, especially in the visual system1-8. Specificity for stimulus attributes clearly implicates an early cortical site, where receptive fields retain fine selectivity for these attributes; however, the neuronal correlates of a simple visual discrimination task remained unidentified. Here we report electrophysiological correlates in the primary visual cortex (V1) of monkeys for learning orientation identification. We link the behavioural improvement in this type of learning to an improved neuronal performance of trained compared to naive neurons. Improved long-term neuronal performance resulted from changes in the characteristics of orientation tuning of individual neurons. More particularly, the slope of the orientation tuning curve that was measured at the trained orientation increased only for the subgroup of trained neurons most likely to code the orientation identified by the monkey. No modifications of the tuning curve were observed for orientations for which the monkey had not been trained. Thus training induces a specific and efficient increase in neuronal sensitivity in V1.