Unconscious Imagination and the Mental Imagery Debate

Abstract

Traditionally, philosophers have appealed to the phenomenological similarity between visual experience and visual imagery to support the hypothesis that there is significant overlap between the perceptual and imaginative domains. The current evidence, however, is inconclusive: while evidence from transcranial brain stimulation seems to support this conclusion, neurophysiological evidence from brain lesion studies (e.g., from patients with brain lesions resulting in a loss of mental imagery but not a corresponding loss of perception and vice versa) indicates that there are functional and anatomical dissociations between mental imagery and perception. Assuming that the mental imagery and perception do not overlap, at least, to the extent traditionally assumed, then the question arises as to what exactly mental imagery is and whether it parallels perception by proceeding via several functionally distinct mechanisms. In this review, we argue that even though there may not be a shared mechanism underlying vision for perception and conscious imagery, there is an overlap between the mechanisms underlying vision for action and unconscious visual imagery. On the basis of these findings, we propose a modification of Kosslyn’s model of imagery that accommodates unconscious imagination and explore possible explanations of the quasi-pictorial phenomenology of conscious visual imagery in light of the fact that its underlying neural substrates and mechanisms typically are distinct from those of visual experience.

Reconstructing imagined letters from early visual cortex reveals tight topographic correspondence between visual mental imagery and perception

“…Both our encoding and reconstruction results show that it is possible to extract similar information from perceived and imagined shapes and are strongly indicative of the pictorial nature of vividly experienced mental images (Brogaard and Gatzia 2017). We further show that the tight topographic correspondence between imagery and perception in early visual cortex allows for improved reconstruction and opens new avenues for decoding.…”

Consciousness and information integration

“…As Milner and Goodale (1995) have argued, action on the fly is governed by unconscious motor representations in the sensorimotor cortex in the vision-for-action stream (see also Goodale et al 1991;Goodale and Milner 1992;Hu and Goodale 2000;Westwood and Goodale 2003). Everyday actions like reaching for your coffee cup, eating with a knife and fork, using a computer mouse, riding your bike, and parking your car on a busy street are not typically preceded by careful planning (Brogaard 2011b;Brogaard and Gatzia 2017). Yet when an action is planned ahead of time, as in the case of following a recipe, playing darts, or making a move in a game of chess, a conscious representation of the planned action helps us execute the action as planned (Brogaard 2011b).…”

Some Hallucinations Are Experiences of the Past

“…The net effect of synaptic tuning varies (see Feldman 2012), but often, the result is that a pattern of activity primes a neural circuit to repeat that pattern when provided part of it as input (Jackson 2013). The standard view is that this pattern completion is what facilitates episodic memory: episodic memories are recalled by repeating the patterns of neural activity that facilitated the original (recalled) sensory interactions (Brogaard and Gatzia 2017, p. 9). The idea is that the original pattern of activity tunes the synaptic weights in relevant memory‐storing areas, leaving behind a memory ‘trace’ or ‘engram’ in the circuit (Liu et al 2014, p. 59).…”