Time to investigate human visual shape perception and recognition

该研究旨在确定视觉信息的性质和时间过程，这些视觉信息对人类视觉对象识别（VOR）的类别专用机制的早期处理路线以及类别专用机制的操作进行视觉识别。我们还旨在研究随着处理在人类皮层视觉区域的层次结构的上升，感受野大小的增加对功能的影响。这些研究将有助于解决与我们对人类VOR系统的一些最基本特征的理解有关的悬而未决的问题。为了确定加工时间过程，我们将使用我们开发的一种新的心理物理学技术，即随机时间采样[见参考文献2]。该方法可以揭示加工有效性如何随着时间的推移而演变，以及加工的时间特征，这些特征在个体之间具有极强的可复制性，并且对刺激类和/或任务参与者执行具有高度的区分性。关于对着VOR的视觉信息，将使用两种方法。一个是使用离散小波分解（DWT）从不同类别（面孔，地点，对象和单词）的大量图像的空间特征的分析。DWT的兴趣在于图像由局部算子（Daubechies小波）处理，该局部算子提供关于图像对比度的尺度（即空间范围）和方向的局部信息。这些功能特征与人类初级视觉皮层（V1）的功能特征相匹配。DWT图像描述将用于表征刺激类别之间的视觉对比以及这些类别中刺激识别所需的歧视类型。另一种方法是理想的观察者模型，其具有无限的处理能力或具有类似于人类低水平视觉编码（即对比度敏感度函数、倾斜效应和随着偏心率的增加而降低的视觉灵敏度）的视觉信息限制。人类参与者和理想观察者的结果之间的差异揭示了人类视觉系统固有的处理限制和/或偏见。拟议的研究将提供一组关于人体VOR基本特性的丰富、可靠的数据。这一结果预计将强烈刺激未来的研究，并有助于制定VOR理论更好的解释能力比今天可用的。COVID 19应急计划：由于COVID 19，我们实验室的三个测试室进行了重组，以便我们可以始终与参与者保持至少2米的距离。目前可用的设备以及我们同时申请的NSERC研究工具和仪器中要求的设备都与该组织完全兼容，因此我们估计未来因大流行而中断实验室操作的可能性极低。

The research proposed aims to determine the nature and time course of the visual information subtending the early routing of processing toward category-specialized mechanisms for visual object recognition (VOR) in humans and the operation of category-specialized mechanisms for the visual recognition of items in terms of their unique identity. We also aim to investigate the functional impact of growing receptive field sizes as processing moves up the hierarchy of visual areas in the human cortex. These studies will help resolve outstanding issues pertaining to our understanding of some of the most fundamental features of the human VOR system. To determine processing time course, we will be using a new psychophysical technique we have developed, which is random temporal sampling [see ref. 2]. This method can reveal how processing effectiveness evolves through time as well as temporal features of processing which are extremely replicable across individuals and also highly discriminant of the stimulus class and/or task participants perform. Regarding the visual information subtending VOR, two approaches will be used. One is the analysis of the spatial features of a large collection of images from different categories (faces, places, objects, and words) using discrete wavelet decomposition (DWT). The interest of DWT is that images are processed by a local operator (Daubechies wavelet) which provides localized information about the scale (i.e. spatial extent) and orientation of image contrasts. These functional features match those of the human primary visual cortex (V1). The DWT image descriptions will serve to characterize the visual contrasts between stimulus categories as well as the types of discrimination required for stimulus identification in these categories. The other method is the ideal observer model with either unlimited processing capacity or with an access to visual information restricted similarly to human low-level visual encoding (i.e. contrast-sensitivity function, oblique effect and reduction of visual acuity with increasing eccentricity). Divergences between the results of human participants and the ideal observers reveal processing limitations and/or biases intrinsic to the human visual system. The studies proposed will offer a rich, robust set of data on fundamental properties of VOR in humans. This outcome is expected to strongly stimulate future research and to contribute to the formulation of VOR theories with better explanatory power than those available today. COVID19 contingency plan: Due to COVID19, the three testing rooms in our lab have been reorganized such that we can maintain a minimum 2 meter distance from participants at all times. Both the equipment presently available and that requested in our concurrent NSERC Research tools and instruments application are fully compatible with this organization and we thus estimate future interruptions in the lab operations due to the pandemic as highly unlikely.