Cardoso-Leite Pedro, Waszak Florian
Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland,
Atten Percept Psychophys. 2014 Jul;76(5):1403-13. doi: 10.3758/s13414-014-0670-y.
A briefly flashed target stimulus can become "invisible" when immediately followed by a mask-a phenomenon known as backward masking, which constitutes a major tool in the cognitive sciences. One form of backward masking is termed metacontrast masking. It is generally assumed that in metacontrast masking, the mask suppresses activity on which the conscious perception of the target relies. This assumption biases conclusions when masking is used as a tool-for example, to study the independence between perceptual detection and motor reaction. This is because other models can account for reduced perceptual performance without requiring suppression mechanisms. In this study, we used signal detection theory to test the suppression model against an alternative view of metacontrast masking, referred to as the summation model. This model claims that target- and mask-related activations fuse and that the difficulty in detecting the target results from the difficulty to discriminate this fused response from the response produced by the mask alone. Our data support this alternative view. This study is not a thorough investigation of metacontrast masking. Instead, we wanted to point out that when a different model is used to account for the reduced perceptual performance in metacontrast masking, there is no need to postulate a dissociation between perceptual and motor responses to account for the data. Metacontrast masking, as implemented in the Fehrer-Raab situation, therefore is not a valid method to assess perceptual-motor dissociations.
当一个短暂闪现的目标刺激紧接着出现一个掩蔽刺激时，它可能会变得“不可见”——这种现象被称为后向掩蔽，它是认知科学中的一种主要工具。后向掩蔽的一种形式被称为元对比掩蔽。一般认为，在元对比掩蔽中，掩蔽刺激会抑制目标刺激有意识感知所依赖的活动。当掩蔽被用作一种工具（例如，用于研究感知检测和运动反应之间的独立性）时，这种假设会使结论产生偏差。这是因为其他模型可以解释感知性能的下降，而无需抑制机制。在本研究中，我们使用信号检测理论，将抑制模型与元对比掩蔽的另一种观点（称为求和模型）进行了测试。该模型声称，与目标和掩蔽相关的激活会融合，并且检测目标的困难源于难以将这种融合反应与仅由掩蔽产生的反应区分开来。我们的数据支持了这一替代观点。本研究并非对元对比掩蔽的全面调查。相反，我们想指出，当使用不同的模型来解释元对比掩蔽中感知性能的下降时，无需假设感知和运动反应之间存在分离来解释数据。因此，在费勒 - 拉布情境中实施的元对比掩蔽不是评估感知 - 运动分离的有效方法。
