 The concept of directness may need some further clarification (and the same goes for the concept of “appropriate immediate sensory input” (Kosslyn et al., 1995, p. 1335, see also Shepard and Metzler 1971) that has also been used to specify what mental imagery lacks). The perceptual processing (in the early cortices) is triggered directly by sensory input if it is triggered without the mediation of some other (perceptual or extra-perceptual) processes. If the perceptual processing is triggered by something non-perceptual (as in the case of closing our eyes and visualizing), it is not triggered either directly or indirectly (see Section 1.3). If the perceptual processing in the visual sense modality is triggered by sensory input in the auditory sense modality (as in the case of an involuntary visual imagery of your face when I hear your voice with my eyes closed), the visual processing is triggered indirectly – with the mediation of auditory processing (see Section 2.2). A direct trigger here would be visual input, but there is no visual input in this case. And if the visual processing at the center of the visual field is triggered by input in the periphery of the visual field (say, because the center of the visual field is occluded by an empty white piece of paper), then the visual processing at the center of the visual field is, again, triggered indirectly, that is, in a way mediated by the visual processes in the periphery (see Section 2.1). A direct trigger would be sensory input at the center of the visual field, but there is no such sensory input in this case. According to the psychological definition of mental imagery, all three of these different examples of perceptual processing count as mental imagery as the perceptual processing is not triggered directly by the sensory input.