Nazir T A, O'Regan J K
Laboratoire de Psychologie Expérimentale, CNRS, Université René Descartes, Paris, France.
Spat Vis. 1990;5(2):81-100. doi: 10.1163/156856890x00011.
Four experiments were conducted to study the nature of visual translation invariance in humans. In all the experiments, subjects were trained to discriminate between a previously unknown target and two non-target distractors presented at a fixed retinal location to one side of the fixation point. In a subsequent test phase, this performance was compared with the performance when the patterns were presented either centrally at the fixation point or at a location on the other side of the fixation point, opposite to the location where the patterns were learned, but where acuity was identical to what it was at the learned location. Two different experimental paradigms were used. One used an eye movement control device (Experiment 1) to ensure the eye could not move relative to the patterns to be learned. In the other three experiments, presentation duration of the patterns was restricted to a short enough period to preclude eye movements. During the training period in Experiments 1 and 2, presentation location of the patterns was centered at 2.4 deg in the periphery, whereas in Experiments 3 and 4 presentation eccentricity was reduced to 0.86 and 0.49 deg. In all four experiments performance dropped when the pattern had to be recognized at new test positions. This result suggests that the visual system does not apply a global transposition transformation to the retinal image to compensate for translations. We propose that, instead, it decomposes the image into simple features which themselves are more-or-less translation invariant. If in a given task, patterns can be discriminated using these simple features, then translation invariance will occur. If not, then translation invariance will fail or be incomplete.
进行了四项实验来研究人类视觉平移不变性的本质。在所有实验中，受试者接受训练，以区分一个先前未知的目标与两个非目标干扰物，这些干扰物呈现于固定视网膜位置，位于注视点一侧。在随后的测试阶段，将这种表现与图案呈现于注视点中央或注视点另一侧位置（与学习图案的位置相对，但该位置的视敏度与学习位置相同）时的表现进行比较。使用了两种不同的实验范式。一种使用眼动控制设备（实验1），以确保眼睛相对于要学习的图案不能移动。在其他三项实验中，图案的呈现持续时间被限制在足够短的时间内，以防止眼动。在实验1和2的训练期间，图案的呈现位置集中在外围2.4度处，而在实验3和4中，呈现偏心率降低到0.86和0.49度。在所有四项实验中，当图案必须在新的测试位置被识别时，表现都会下降。这一结果表明，视觉系统不会对视网膜图像应用全局转置变换来补偿平移。我们提出，相反，它会将图像分解为本身或多或少具有平移不变性的简单特征。如果在给定任务中，可以使用这些简单特征来区分图案，那么就会出现平移不变性。如果不能，那么平移不变性将会失效或不完整。
