Elucidating unconscious processing with instrumental hypnosis

Abstract

Most researchers leverage bottom-up suppression to unlock the underlying mechanisms of unconscious processing. However, a top-down approach - for example via hypnotic suggestion - paves the road to experimental innovation and complementary data that afford new scientific insights concerning attention and the unconscious. Drawing from a reliable taxonomy that differentiates subliminal and preconscious processing, we outline how an experimental trajectory that champions top-down suppression techniques, such as those practiced in hypnosis, is uniquely poised to further contextualize and refine our scientific understanding of unconscious processing. Examining subliminal and preconscious methods, we demonstrate how instrumental hypnosis provides a reliable adjunct that supplements contemporary approaches. Specifically, we provide an integrative synthesis of the advantages and shortcomings that accompany a top-down approach to probe the unconscious mind. Our account provides a larger framework for complementing the results from core studies involving prevailing subliminal and preconscious techniques.

Keywords: consciousness; global workspace; instrumental hypnosis; preconscious processing; subliminal perception; suggestion; suppression of consciousness; unconscious.

FIGURE 1

Contemporary approaches and the hypnotic approach as a function of the taxonomy that differentiates subliminal processing, reflecting perceptual failures, from preconscious processing, reflecting attentional failures. During subliminal processing: contemporary approaches utilize bottom-up competition between sensory inputs to exploit the limits of perception, prevent global broadcast of incoming signals and induce conscious suppression; while the hypnotic approach harness top-down processes to modulate lower perceptual processes and suppress sensory inputs. During preconscious processing: both contemporary approaches and the hypnotic approach prevent global broadcast by hindering top-down amplification of incoming sensory signals.

FIGURE 2

Subliminal techniques. A sketch of the prevailing techniques used to suppress conscious perception of sensory inputs. (A1) Binocular rivalry where dichoptic presentation of dissimilar stimuli generates fluctuation in conscious perception between representations. (A2) Continuous flash suppression where presentation a repeatedly flashed stimulus to one eye induces conscious suppression of static stimulus presented in the other eye.(B) Backward masking where rapid sequential presentation of a prime and a mask conscious induces conscious suppression of the prime. (C) Visual crowding where flankers interfere with processing of the target in peripheral vision, rendering certain target-related characteristics unrecognizable. (D) Bistable figures induce perceptual fluctuations between mutually exclusive visual interpretations – e.g., side A facing upward and then facing downward. (E) Motion-induced blindness where movement of the global pattern suppresses conscious perception of the targets.

FIGURE 3

Strengths and weaknesses of contemporary techniques to investigate unconscious perception and instrumental hypnosis as a function of evaluation criteria. Generality: whether the technique applies to a broad range of stimuli or only to a selected few. Location of stimulus: whether the stimulus has to be presented at the center or the periphery of the visual field to induce conscious suppression or inattention. Temporal constraint: whether the technique imposes a temporal constraint relative to the duration of the stimulus presentation. Robustness: whether the technique completely abolishes awareness. Invariant stimulation: whether conscious suppression requires significant modifications of sensory events to make a stimulus invisible. A “✓” indicates that the technique meets this particular criterion, whereas an “×” indicates that the technique fails to meet this particular criterion.

FIGURE 4

Hypnotic suggestions divide as a function of type and content. These various hypnotic suggestions yield numerous hypnotic effects.

FIGURE 5

Balanced experimental design using instrumental hypnosis where contrast between conscious suppression – i.e., stimulus is present and consciousness is absent – and conscious hallucination – i.e., stimulus is absent and consciousness is present – enable targeting of neural correlates of consciousness.