2020/11/2
Size matters-On human understanding of the spatial extent of objects
【演講公告】
系上很榮幸地邀請國立臺灣大學心理學系陳建中老師至系上演講，
系上很榮幸地邀請國立臺灣大學心理學系陳建中老師至系上演講，
演講相關內容如下：
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時間：11/06（五）13：10
地點：社科院北棟2樓心理系階梯教室
講者：陳建中老師 （國立臺灣大學心理學系 特聘教授）
講題：Size matters – On human understanding of the spatial extent of objects
演講摘要：
Here, I approached the internal representation of objects with two different approaches. The first is spatial summation, in which we measured the contrast detection thresholds for targets of various size. The targets could be Gaussian spots, Gabor patterns, texts, or faces. In general, the detection threshold first decreased with target length with slope -1 until a critical size and then turn slope −1/2 on log-log coordinates. The -1/2 slope defined a range of ideal matched-filter summation extending up to about 200′. Under external noise, the summation curves for different noise contrasts were shifted copies of each other. For the threshold versus mask contrast (TvN) functions, the target threshold was constant for noise levels up to about− 22 dB, then increased with noise contrast to a linear asymptote on log-log coordinates. Since the “elbow” of the target threshold versus noise function is an index of the level of the equivalent noise experienced by the visual system during target detection, our results suggest that the signal-to-noise ratio was invariant with target length. We further show that a linear-nonlinear-linear gain-control model can fully account for these results with far fewer parameters than a matched-filter model.
The second approach is to measure perceived size under various contexts. We first investigated the effect of the size distribution the first, second, and third order statistics (i.e., mean, variance, and skewness) of background elements on the perceived size of a target. We measured the point of subjective equality for the perceived target size with a staircase procedure. The perceived target size decreased with the increment of mean background disk size. The variance and skewness of the background element size did not affect the perceived target size. Our results showed that only the first order statistics of the background modulated the perceived target size, not the higher order statistics. A computational model, in which the visual system extracts size information by averaging the responses of different size channels, whose response is modulated by the size of the background elements, can account for the results.
個人簡介或CV：【學經歷、研究興趣、著作等】
1996年：加州大學聖塔芭芭拉分校心理學博士
1994年：加州大學聖塔芭芭拉分校心理學碩士
1989年：臺大心理系學士
2003- : 國立臺灣大學心理學系
2002-2003年：舊金山史密斯·基特韋爾眼科研究所，進行視覺功能磁共振成像的計算分析。
2002年：加州大學伯克萊分校視覺科學系，進行多焦點腦電波圖（EEG）來源定位。 （與神經測量學研究所聯合任命）
2001-2002：神經測量學會。磁振造影（MRI）的工作限制了高分辨率腦電波圖（EEG）來源的定位。
1999-2000：英國哥倫比亞大學眼科學院與黛博拉(Deborah Giaschi)博士一起進行讀寫障礙的MRI研究
1997-1999：史密斯·凱特韋爾眼科研究中心。與克里斯托弗·泰勒（Christopher W. Tyler）博士一起探討視覺心理物理學和神經生理學的計算模型。
個人網站：
http://www.psy.ntu.edu.tw/vnl/index.html
參考文獻：
Chen CC, Yeh YH, Tyler CW (2019). Length summation in noise. Journal of Vision 19(9):11. doi: https://doi.org/10.1167/19.9.11.
Wu, C., Chen, C. (2018). The Effect of Size Statistics of the Background Texture on Perceived Target Size. Sci Rep 8, 10963. https://doi.org/10.1038/s41598-018-29168-1
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敬請準時出席，謝謝。