Unconscious processing of color and form in metacontrast masking

T. Ro; N. S. Singhal; B. G. Breitmeyer; J. O. Garcia

doi:10.3758/app.71.1.95

TMS of V1 eliminates unconscious processing of chromatic stimuli

10.1101/606095 ◽

2019 ◽

Author(s):

Mikko Hurme ◽

Mika Koivisto ◽

Linda Henriksson ◽

Henry Railo

Keyword(s):

Reaction Times ◽

The Unconscious ◽

Unconscious Processing ◽

Metacontrast Masking ◽

Chromatic Stimulus ◽

Redundant Target Effect ◽

Visual Mask ◽

Neurological Patients ◽

Target Effect ◽

Healthy Participants

AbstractSome of the neurological patients with primary visual cortex (V1) lesions can guide their behavior based on stimuli presented to their blind visual field. One example of this phenomenon is the ability to discriminate colors in the absence of awareness. These so-called patients with blindsight must have a neural pathway that bypasses the V1, explaining their ability to unconsciously process stimuli. To test if similar pathways function in neurologically healthy individuals or if unconscious processing depends on the V1, we disturbed the visibility of a chromatic stimulus with metacontrast masking (Experiment 1) or transcranial magnetic stimulation (TMS) of the V1 (Experiment 2). We measured unconscious processing using the redundant target effect (RTE), which is the speeding up of reaction times in response to dual stimuli compared with one stimulus, when the task is to respond to any number of stimuli. An unconscious chromatic RTE was found when the visibility of the redundant chromatic stimulus was suppressed with a visual mask. When TMS was applied to the V1 to disturb the perception of the redundant chromatic stimulus, the RTE was eliminated. Based on our results and converging evidence from previous studies, we conclude that the unconscious processing of chromatic information depends on the V1 in neurologically healthy participants.

Download Full-text

Unconscious Processing of Unattended Features in Human Visual Cortex

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_00320 ◽

2013 ◽

Vol 25 (3) ◽

pp. 329-337 ◽

Cited By ~ 2

Author(s):

Tatiana Aloi Emmanouil ◽

Philip Burton ◽

Tony Ro

Keyword(s):

Visual Cortex ◽

Visual Features ◽

Multiple Features ◽

Priming Effects ◽

Unconscious Processing ◽

Metacontrast Masking ◽

Visual Areas ◽

Human Participants ◽

Task Irrelevant ◽

And Task

Unconscious processing has been convincingly demonstrated for task-relevant feature dimensions. However, it is possible that the visual system is capable of more complex unconscious operations, extracting visual features even when they are unattended and task irrelevant. In the current study, we addressed this question by measuring unconscious priming using a task in which human participants attended to a target object's shape while ignoring its color. We measured both behavioral priming effects and priming-related fMRI activations from primes that were unconsciously presented using metacontrast masking. The results showed faster RTs and decreases in fMRI activation only when the primes were identical to the targets, indicating that primes were processed both in the attended shape and the unattended color dimensions. Reductions in activation were observed in early visual areas, including primary visual cortex, as well as in feature-responsive areas for shape and color. These results indicate that multiple features can be unconsciously encoded and possibly bound using the same visual networks activated by consciously perceived images.

Download Full-text

“The Unconscious” in Current Psychology

European Psychologist ◽

10.1027/1016-9040/a000017 ◽

2010 ◽

Vol 15 (3) ◽

pp. 193-201 ◽

Cited By ~ 17

Author(s):

Elisabeth Norman

Keyword(s):

Cognitive Psychology ◽

Verbal Report ◽

Psychological Research ◽

Operational Definition ◽

The Unconscious ◽

Apparent Lack ◽

Unconscious Processing ◽

Unconscious Processes ◽

Intermediate States ◽

Definition Of

A series of vignette examples taken from psychological research on motivation, emotion, decision making, and attitudes illustrates how the influence of unconscious processes is often measured in a range of different behaviors. However, the selected studies share an apparent lack of explicit operational definition of what is meant by consciousness, and there seems to be substantial disagreement about the properties of conscious versus unconscious processing: Consciousness is sometimes equated with attention, sometimes with verbal report ability, and sometimes operationalized in terms of behavioral dissociations between different performance measures. Moreover, the examples all seem to share a dichotomous view of conscious and unconscious processes as being qualitatively different. It is suggested that cognitive research on consciousness can help resolve the apparent disagreement about how to define and measure unconscious processing, as is illustrated by a selection of operational definitions and empirical findings from modern cognitive psychology. These empirical findings also point to the existence of intermediate states of conscious awareness, not easily classifiable as either purely conscious or purely unconscious. Recent hypotheses from cognitive psychology, supplemented with models from social, developmental, and clinical psychology, are then presented all of which are compatible with the view of consciousness as a graded rather than an all-or-none phenomenon. Such a view of consciousness would open up for explorations of intermediate states of awareness in addition to more purely conscious or purely unconscious states and thereby increase our understanding of the seemingly “unconscious” aspects of mental life.

Download Full-text