Multisensory enhancement elicited by unconscious visual stimuli

Abstract

The merging of information from different senses (i.e., multisensory integration) can facilitate information processing. Processing enhancements have been observed with signals that are irrelevant to the task at hand, and with cues that are non-predictive. Such findings are consistent with the notion that multiple sensory signals are sometimes integrated automatically. Multisensory enhancement has even been reported with stimuli that have been presented subliminally, though only with meaningful multisensory relations that have already been learned. The question of whether there exist cases where multisensory effects occur without either learning or awareness has, though, not been clearly established in the literature to date. Here, we present a case study of a patient with Posterior Cortical Atrophy, who was unable to consciously perceive visual stimuli with our task parameters, yet who nevertheless still exhibited signs of multisensory enhancement even with unlearned relations between audiovisual stimuli. In a simple speeded detection task, both response speed, and the variability of reaction times, decreased in a similar manner to controls for multisensory stimuli. These results are consistent with the view that the conscious perception of stimuli and prior learning are not always a prerequisite for multisensory integration to enhance human performance.

Context-dependent cross-modal interaction in the medial prefrontal cortex of rats

“…When performing the task, rats showed shorter reaction times in multisensory conditions. This result is consistent with what was observed in many previous studies conducted in both humans and animals [40][41][42][43]. Of especial relevance to our finding here, it has been shown that a task-irrelevant auditory stimulus could shorten the reaction time of responding to visual cues [44] and multisensory processing of both semantic congruent and incongruent stimuli could speed up reaction time [42].…”

An Experimenter's Influence on Motor Enhancements: The Effects of Letter Congruency and Sensory Switch-Costs on Multisensory Integration

“…However, unusually high RT variability was noted in this first attempt compared to the previous studies by Barutchu et al in which the experimenter was seated in the room with the participant, the most obvious explanation being the absence of the experimenter from the testing room (e.g., Barutchu et al, 2009Barutchu et al, , 2018. Within the multisensory literature, in studies that test children and clinical patients, for reasons of practicality, participants are often closely monitored with the experimenter or caregiver typically seated in the room (e.g., Barutchu et al, 2009Barutchu et al, , 2018Bremner et al, 2012). However, in adult studies, participants are typically left alone during the testing phase of any experiment.…”

“…Initially, the two experiments reported here were designed to replicate prior findings by Otto and Mamassian, and the experiment was conducted with the participants left alone in a quiet isolated room (e.g., Otto and Mamassian, 2012). However, unusually high RT variability was noted in this first attempt compared to the previous studies by Barutchu et al in which the experimenter was seated in the room with the participant, the most obvious explanation being the absence of the experimenter from the testing room (e.g., Barutchu et al, 2009Barutchu et al, , 2018. Within the multisensory literature, in studies that test children and clinical patients, for reasons of practicality, participants are often closely monitored with the experimenter or caregiver typically seated in the room (e.g., Barutchu et al, 2009Barutchu et al, , 2018Bremner et al, 2012).…”

“…To the best of our knowledge, no one has yet explicitly investigated the effects of the presence of an experimenter on multisensory information processing. Therefore, we re-ran the studies replicating prior experimental conditions, but with the experimenter now seated in the room, out of sight of the participant, with the idea being subtly to encourage the participants to maintain their vigilance and attention during the task (e.g., Barutchu et al, 2009Barutchu et al, , 2018. Understanding the influence of the experimenter is undoubtedly an important contribution to the literature as multisensory processes in everyday life typically occur in social situations, whereas the experimental participant is often isolated from any social interaction (Soto-Faraco et al, 2019).…”

Subliminal Priming—State of the Art and Future Perspectives

“…Priming refers to an increased sensitivity to certain stimuli, resulting from prior exposure to related visual or audio messages [ 1 ]. When an individual is exposed to the word “cancer”, for example, and then offered the choice to smoke a cigarette, we expect that there is a greater probability that they will choose not to smoke as a result of the earlier exposure.…”