Friesen Chris Kelland, Kingstone Alan
Depatment of Psychology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Neuroreport. 2003 Mar 3;14(3):489-93. doi: 10.1097/00001756-200303030-00039.
We examined covert and overt orienting in response to non-predictive gaze direction cues and investigated whether the subcortical superior colliculus (SC) plays a role in this type of orienting. Participants viewed a centrally presented gazing schematic face and responded to targets appearing at gazed-at or non-gazed-at locations either by making a keypress response while maintaining central fixation or by making an eye movement to the target. For both response conditions, the fixation stimulus (the gazing face) either remained on the screen or was extinguished at the time of target presentation, a manipulation known to engage and disengage the SC. Results revealed that participants making manual responses oriented covertly to the gazed-at location regardless of the fixation condition, and that participants making eye movements oriented overtly only if the fixation stimulus remained on the screen. Overt gaze-triggered orienting was not enhanced relative to covert orienting, and the fixation offset effect was not reduced for averted gaze cues relative to straight gaze cues. These findings suggest that gaze direction cues do not activate or predisengage the oculomotor system, and thus that orienting to gaze direction does not engage the SC. This is consistent with the view that gaze-triggered orienting is a unique form of reflexive orienting that depends crucially on cortical processes.
我们研究了对非预测性注视方向线索的隐蔽和显性定向，并调查了皮层下上丘（SC）是否在这类定向中发挥作用。参与者观看一个呈现在中央的注视示意图脸，并对出现在注视或未注视位置的目标做出反应，要么在保持中央注视的同时按下按键做出反应，要么向目标进行眼动。对于这两种反应条件，注视刺激（注视脸）要么在屏幕上保持显示，要么在目标呈现时消失，这是一种已知的用于激活和解除上丘参与的操作。结果显示，做出手动反应的参与者无论注视条件如何都会隐蔽地定向到注视位置，而做出眼动反应的参与者只有在注视刺激保持在屏幕上时才会显性地定向。相对于隐蔽定向，由注视触发的显性定向并未增强，并且相对于直视线索，回避注视线索的注视偏移效应并未降低。这些发现表明，注视方向线索不会激活或预先解除眼动系统，因此对注视方向的定向不会涉及上丘。这与以下观点一致，即由注视触发的定向是一种独特的反射性定向形式，它关键取决于皮层过程。
