Interocular transfer in perceptual learning of a pop-out discrimination task.

Abstract

The specificity of the improvement in perceptual learning is often used to localize the neuronal changes underlying this type of adult plasticity. We investigated a visual texture discrimination task previously reported to be accomplished preattentively and for which learning-related changes were inferred to occur at a very early level of the visual processing stream. The stimulus was a matrix of lines from which a target popped out, due to an orientation difference between the three target lines and the background lines. The task was to report the global orientation of the target and was performed monocularly. The subjects' performance improved dramatically with training over the course of 2-3 weeks, after which we tested the specificity of the improvement for the eye trained. In all subjects tested, there was complete interocular transfer of the learning effect. The neuronal correlates of this learning are therefore most likely localized in a visual area where input from the two eyes has come together.The specificity of improvement in performance with perceptual training is widely regarded as the key to the neurological localization of the learning effect. For simple tasks, the learning effect is specific for some particular stimulus attributes, such as orientation (1-3) and spatial frequency (4). Moreover, the improvement in performance observed in these simple tasks remains restricted to stimulus position in the subject's visual field (3-8). By contrast, for more complex tasks, the learned improvement transferred to different stimulus attributes as well as to other positions in the visual field (9).Specificity of the learning effect to particular stimulus attributes and to stimulus position implies that the improvement in performance is due to changes in populations of neurons at early stages of the visual pathway, where neurons are highly specialized for simple stimulus attributes and for stimulus position and size, in contrast to neurons in higher visual areas, which generalize over these stimulus variables.

Transfer of learning across durations and ears in auditory frequency discrimination

“…In regard to the transfer of learning between ears, the results of Experiment 1 showed that following training, FDTs were overall as small in the left, untrained ear as in the right, trained ear. This finding of learning transfer between ears for auditory frequency discrimination can be paralleled with the findings of learning transfer between eyes for various visual tasks (Ball & Sekuler, 1987;Berardi & Fiorentini, 1987;Schoups & Orban, 1996) and between hands for tactile discrimination (Sathian & Zangaladze, 1997;Spengler et al, 1997).…”

Generalization of Frequency Discrimination Learning Across Frequencies and Ears: Implications for Underlying Neural Mechanisms in Humans

“…In the visual modality, for instance, spectacular perceptual-learning effects have been demonstrated in texture-, contrast-, orientation-, or movement-discrimination tasks (e.g., Ahissar andHochstein 1996, 1997;Ball and Sekuler 1982;Berardi 1980, 1981;Sagi 1991, 1993;Karni and Bertini 1997;Schoups and Orban 1996;Ahissar 2001;Gilbert 1994Gilbert , 1996. In the auditory modality, considerable improvements in thresholds with practice have been shown in frequency-and duration-discrimination tasks (Ari-Even Roth et al 2003;Campbell and Small 1963;Delhommeau et al 2002;Demany 1985;Demany and Semal 2002;Grimault et al 2002Grimault et al , 2003Hawkey et al 2004;Irvine et al 2000;Wright and Fitzgerald 2005;Wright et al 1997).…”

Multiple groups of orientation–selective visual mechanisms underlying rapid orientated–line detection

“…Observers were not given feedback. As there have been reports of learning in orientated-linedetection tasks (Karni & Sagi 1991;Schoups & Orban 1996;Ahissar & Hochstein 1997), the data were tested for evidence of practice e¡ects. A small improvement in performance was found: thresholds over each observer's ¢rst 5000 trials were, on average, about 10% higher than over the remaining trials, although the e¡ect did not reach signi¢cance (t 9 1X36, p 0X1).…”