Wiens Stefan
Department of Psychology, Stockholm University, Frescati Hagväg, 106 91 Stockholm, Sweden.
Prog Brain Res. 2006;156:105-21. doi: 10.1016/S0079-6123(06)56006-6.
Many theories of emotion propose that emotional input is processed preferentially due to its relevance for the organism. Further, because consciousness has limited capacity, these considerations imply that emotional input ought to be processed even if participants are perceptually unaware of the input (subliminal perception). Although brain imaging has studied effects of unattended, suppressed (in binocular rivalry), and visually masked emotional pictures, conclusions regarding subliminal perception have been mixed. The reason is that subliminal perception demands a concept of an awareness threshold or limen, but there is no agreement on how to define and measure this threshold. Although different threshold concepts can be identified in psychophysics (signal detection theory), none maps directly onto perceptual awareness. Whereas it may be tempting to equate unawareness with the complete absence of objective discrimination ability (d'=0), this approach is incompatible with lessons from blindsight and denies the subjective nature of consciousness. This review argues that perceptual awareness is better viewed as a continuum of sensory states than a binary state. When levels of awareness are characterized carefully in terms of objective discrimination and subjective experience, findings can be informative regarding the relative independence of effects from awareness and the potentially moderating role of awareness in processing emotional input. Thus, because the issue of a threshold concept may never be resolved completely, the emphasis is to not prove subliminal perception but to compare effects at various levels of awareness.
许多情绪理论认为，由于情绪输入与机体的相关性，它会被优先处理。此外，由于意识的容量有限，这些因素意味着即使参与者在感知上未意识到该输入（阈下知觉），情绪输入也应该被处理。尽管脑成像研究了未被注意、被抑制（在双眼竞争中）以及视觉掩蔽的情绪图片的影响，但关于阈下知觉的结论却参差不齐。原因在于阈下知觉需要一个意识阈限的概念，但对于如何定义和测量这个阈限尚无共识。虽然在心理物理学（信号检测理论）中可以识别出不同的阈限概念，但没有一个能直接映射到知觉意识上。虽然将无意识等同于完全缺乏客观辨别能力（d' = 0）可能很诱人，但这种方法与盲视的教训相悖，并且否认了意识的主观本质。本综述认为，知觉意识更应被视为一种连续的感觉状态，而非二元状态。当根据客观辨别和主观体验仔细刻画意识水平时，研究结果对于意识效应的相对独立性以及意识在处理情绪输入中可能的调节作用会具有启发性。因此，由于阈限概念的问题可能永远无法完全解决，重点不在于证明阈下知觉，而在于比较不同意识水平下的效应。
