Journal of Vision (2016)
Denise Moerel, Sam Ling & Janneke Jehee
Visual orientation discrimination is known to improve with extensive training, but the mechanisms underlying this behavioral benefit remain poorly understood. Here, we examine the possibility that more reliable task performance could arise in part because observers learn to sample information from a larger portion of the stimulus. We used a variant of the classification image method in combination with a global orientation discrimination task to test whether a change in information sampling underlies training-based benefits in behavioral performance. The results revealed that decreases in orientation thresholds with perceptual learning were accompanied by increases in stimulus sampling. In particular, while stimulus sampling was restricted to the parafoveal, inner portion of the stimulus before training, we observed an outward spread of sampling after training. These results demonstrate that the benefits of perceptual learning may arise, in part, from a strategic increase in the efficiency with which the observer samples information from a visual stimulus.
Journal of Neuroscience (2015)
Tim Kietzmann, Sonia Poltoratski, Peter König, Randolph Blake, Frank Tong & Sam Ling
Humans reliably recognize faces across a range of viewpoints, but the neural substrates supporting this ability remain unclear. Recent work suggests that neural selectivity to mirror-symmetric viewpoints of faces, found across a large network of visual areas, may constitute a key computational step in achieving full viewpoint invariance. In this study, we used repetitive transcranial magnetic stimulation (rTMS) to test the hypothesis that the occipital face area (OFA), putatively a key node in the face network, plays a causal role in face viewpoint symmetry perception. Each participant underwent both offline rTMS to the right OFA and sham stimulation, preceding blocks of behavioral trials. After each stimulation period, the participant performed one of two behavioral tasks involving presentation of faces in the peripheral visual field: judging the viewpoint symmetry or judging the angular rotation. rTMS applied to the right OFA significantly impaired performance in both tasks when stimuli were presented in the contralateral, left visual field. Interestingly, however, rTMS had a differential effect on the two tasks performed ipsilaterally. While viewpoint symmetry judgments were significantly disrupted, we observed no impact on the angle judgment task. This interaction, caused by ipsilateral rTMS, provides support for models emphasizing the role of inter-hemispheric crosstalk in the formation of viewpoint-invariant face perception.
Dongho’s own crystal brain:
Dongho Kim has moved to Seoul to begin his new adventure as MR Scientific Consultant at ASAN Medical Center. We’ll miss having you around Dongho!
Sam was selected as a 2015 Hariri Institute Junior Faculty Fellows. The program recognizes junior faculty at Boston University working in diverse areas of computing and the computational sciences. Institute Fellows help connect like-minded researchers at BU and beyond, also providing a focal point for supporting broader collaborative research.
Official announcement here: http://www.bu.edu/hic/2015/09/28/institute-announces-2015-junior-faculty-fellows/
More info on the Peter Paul Award (and a brief interview) here: http://www.bu.edu/today/2015/four-junior-faculty-awarded-peter-paul-professorships/