Mental images are neither seen nor unseen: demystifying quasi-sensory experience

Mental images have a distinctive, ethereal appearance that is neither clearly visible nor invisible. This article proposes that mental images involve quasi-sensory experiences of thought content without experiencing basic visual features like color or shape. Quasi-sensory experiences are common in everyday perception, such as the fluctuating experience when viewing bistable illusions like the rabbit-duck, or the inaccessible features in associative agnosia. These experiences are conscious, somewhat visual (occurring within the visual field), yet distinct from perceiving basic visual features. Viewing mental imagery as quasi-sensory aligns with neuropsychological evidence showing it requires mid- and late-stage visual processing, not early-stage. This account may help individuals differentiate whether they experience typical mental images or define them differently.

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Abstract

A typical mental image is not clearly visible, nor invisible, but instead has an ethereal, near-indescribable appearance. This article attempts to define specifically what this phenomenology seems to entail. Here, mental images are proposed to involve only quasi-sensory experiences of thought content, without experiencing basic visual features of that content. Quasi-sensory experiences are ubiquitous components of everyday perception, such as those which fluctuate when viewing bistable images (e.g., the rabbit-duck illusion), or which are inaccessible during object recognition in associative agnosia. They are (1) conscious experiences that are (2) at least somewhat visual, in that their content is experienced within the visual field, but they are also (3) distinct from experiencing basic visual features of real or imagined content in the visual field. Such experiences are neither maximally sensory (depictive), nor non-sensory (non-depictive). Viewing mental imagery as quasi-sensory aligns with neuropsychological evidence showing that mental imagery requires mid- and late-stage, not early-stage, visual processing, and supersedes explanations for mental imagery’s ethereal phenomenology based on low-level feature coarseness (e.g., blurriness, dimness), opacity, unreality, or voluntariness. By equating mental image phenomenology to components of other ordinary perceptual experiences, this account could help individuals differentiate if they can or cannot experience a typical mental image, or if they have merely defined a typical mental image differently to another person. Ultimately, experiencing a mental image as quasi-sensory, as described here, would not clearly constitute seeing, nor not seeing, potentially resolving decades of confusion around the format of mental images.