Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Ophthalmology, perceptual learning, task irrelevant learning, object recognition, tDCS, DIRECT-CURRENT STIMULATION, PRIMARY VISUAL-CORTEX, EXTRASTRIATE CORTEX, MOTOR CORTEX, RECOGNITION, DISCRIMINATION, ORIENTATION, INVARIANT, REPRESENTATIONS, EXCITABILITY, Adolescent, Adult, Female, Humans, Learning, Male, Occipital Lobe, Orientation, Photic Stimulation, Transcranial Direct Current Stimulation, Visual Perception, Young Adult, 11 Medical and Health Sciences, 17 Psychology and Cognitive Sciences, Experimental Psychology, 3212 Ophthalmology and optometry

Abstract:

During perceptual learning the visual representations in the brain are altered, but these changes' causal role has not yet been fully characterized. We used transcranial direct current stimulation (tDCS) to investigate the role of higher visual regions in lateral occipital cortex (LO) in perceptual learning with complex objects. We also investigated whether object learning is dependent on the relevance of the objects for the learning task. Participants were trained in two tasks: object recognition using a backward masking paradigm and an orientation judgment task. During both tasks, an object with a red line on top of it were presented in each trial. The crucial difference between both tasks was the relevance of the object: the object was relevant for the object recognition task, but not for the orientation judgment task. During training, half of the participants received anodal tDCS stimulation targeted at the lateral occipital cortex (LO). Afterwards, participants were tested on how well they recognized the trained objects, the irrelevant objects presented during the orientation judgment task and a set of completely new objects. Participants stimulated with tDCS during training showed larger improvements of performance compared to participants in the sham condition. No learning effect was found for the objects presented during the orientation judgment task. To conclude, this study suggests a causal role of LO in relevant object learning, but given the rather low spatial resolution of tDCS, more research on the specificity of this effect is needed. Further, mere exposure is not sufficient to train object recognition in our paradigm.