TMS of V1 eliminates unconscious processing of chromatic stimuli

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.

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Multisensory stimuli shift perceptual priors to facilitate rapid behavior

Scientific Reports ◽

10.1038/s41598-021-02566-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

John Plass ◽

David Brang

Keyword(s):

Cortical Excitability ◽

Reaction Times ◽

Stimulus Onset ◽

Stimulus Sequence ◽

Phase Resetting ◽

Redundant Target Effect ◽

Sequence Effects ◽

Multisensory Interactions ◽

Sensory Responses ◽

Target Effect

AbstractMultisensory stimuli speed behavioral responses, but the mechanisms subserving these effects remain disputed. Historically, the observation that multisensory reaction times (RTs) outpace models assuming independent sensory channels has been taken as evidence for multisensory integration (the “redundant target effect”; RTE). However, this interpretation has been challenged by alternative explanations based on stimulus sequence effects, RT variability, and/or negative correlations in unisensory processing. To clarify the mechanisms subserving the RTE, we collected RTs from 78 undergraduates in a multisensory simple RT task. Based on previous neurophysiological findings, we hypothesized that the RTE was unlikely to reflect these alternative mechanisms, and more likely reflected pre-potentiation of sensory responses through crossmodal phase-resetting. Contrary to accounts based on stimulus sequence effects, we found that preceding stimuli explained only 3–9% of the variance in apparent RTEs. Comparing three plausible evidence accumulator models, we found that multisensory RT distributions were best explained by increased sensory evidence at stimulus onset. Because crossmodal phase-resetting increases cortical excitability before sensory input arrives, these results are consistent with a mechanism based on pre-potentiation through phase-resetting. Mathematically, this model entails increasing the prior log-odds of stimulus presence, providing a potential link between neurophysiological, behavioral, and computational accounts of multisensory interactions.

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Multisensory Stimuli Shift Perceptual Priors to Favor Rapid Detection

10.31234/osf.io/s9rdq ◽

2021 ◽

Author(s):

John Plass ◽

David Brang

Keyword(s):

Cortical Excitability ◽

Reaction Times ◽

Stimulus Onset ◽

Stimulus Sequence ◽

Phase Resetting ◽

Redundant Target Effect ◽

Sequence Effects ◽

Multisensory Interactions ◽

Sensory Responses ◽

Target Effect

Multisensory stimuli speed behavioral responses, but the mechanisms subserving these effects remain disputed. Historically, the observation that multisensory reaction times (RTs) outpace models assuming independent sensory channels has been taken as evidence for multisensory integration (the “redundant target effect”; RTE). However, this interpretation has been challenged by alternative explanations based on stimulus sequence effects, RT variability, and/or negative correlations in unisensory processing. To clarify the mechanisms subserving the RTE, we collected RTs from 78 undergraduates in a multisensory simple RT task. Based on previous neurophysiological findings, we hypothesized that the RTE was unlikely to reflect these alternative mechanisms, and more likely reflected pre-potentiation of sensory responses through crossmodal phase-resetting. Contrary to accounts based on stimulus sequence effects, we found that preceding stimuli explained only 3-9% of the variance in apparent RTEs. Comparing three plausible evidence accumulator models, we found that multisensory RT distributions were best explained by increased sensory evidence at stimulus onset. Because crossmodal phase-resetting increases cortical excitability before sensory input arrives, these results are consistent with a mechanism based on pre-potentiation through phase-resetting. Mathematically, this model entails increasing the prior log-odds of stimulus presence, providing a potential link between neurophysiological, behavioral, and computational accounts of multisensory interactions.

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“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.

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The self-face captures attention without consciousness: evidence from the N2pc ERP component analysis

10.1101/2020.01.22.915595 ◽

2020 ◽

Author(s):

Michał Bola ◽

Marta Paź ◽

Łucja Doradzińska ◽

Anna Nowicka

Keyword(s):

Face Image ◽

The Self ◽

The Unconscious ◽

Face Analysis ◽

Unconscious Processing ◽

Familiar Face ◽

Probe Experiment ◽

Early Processing ◽

Own Name ◽

Key Questions

AbstractIt is well established that stimuli representing or associated with ourselves, like our own name or an image of our own face, benefit from preferential processing. However, two key questions concerning the self-prioritization mechanism remain to be addressed. First, does it operate in an automatic manner during the early processing, or rather in a more controlled fashion at later processing stages? Second, is it specific to the self-related stimuli, or can it be activated also by other stimuli that are familiar or salient? We conducted a dot-probe experiment to investigate the mechanism behind attentional prioritization of the selfface image and to tackle both questions. The former, by employing a backwards masking procedure to isolate the early and preconscious processing stages. The latter, by investigating whether a face that becomes visually familiar due to repeated presentations is able to capture attention in a similar manner as the self-face. Analysis of the N2pc ERP component revealed that the self-face image automatically captures attention, both when processed consciously and unconsciously. In contrast, the visually familiar face did not attract attention, neither in the conscious, nor in the unconscious condition. We conclude that the selfprioritization mechanism is early and automatic, and is not triggered by a mere visual familiarity. More generally, our results provide further evidence for efficient unconscious processing of faces, and for a dissociation between attention and consciousness.

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Behavioral effects of sub-anesthetic ketamine in a go/no-go task

Journal of Psychedelic Studies ◽

10.1556/2054.2020.00126 ◽

2021 ◽

Vol 4 (3) ◽

pp. 156-162

Author(s):

André Sevenius Nilsen ◽

Bjørn Erik Juel ◽

Nadine Farnes ◽

Luis Romundstad ◽

Johan Frederik Storm

Keyword(s):

Reaction Times ◽

Behavioral Effects ◽

Behavioral Performance ◽

Altered States ◽

States Of Consciousness ◽

Performance Impairment ◽

Motor Response Inhibition ◽

Omission Errors ◽

Drug Free ◽

Healthy Participants

AbstractBackground and aimsWhile psychedelic agents are known to have powerful, but largely unexplained, effects on contents of consciousness, there is an increasing interest in the potential clinical usefulness of such drugs for therapy, and legalization is discussed in some countries. Thus, it is relevant to study the effects of psychedelic compounds not only on experience, but also on behavioral performance.MethodsSeven healthy participants performed a motor response inhibition task before, during, and after sub-anesthetic doses of intravenously administered ketamine. The infusion rate was individually adjusted to produce noticeable subjective psychedelic effects.ResultsWe observed no statistically significant impact of sub-anesthetic ketamine on reaction times, omission errors, or post error slowing, relative to the preceding drug-free condition. However, we did observe significant correlations between performance impairment and self-reported, subjective altered states of consciousness, specifically experience of “anxiety” and “complex imagery.”ConclusionsConsidering the limited number of participants and large variation in strength of self-reported experiences, further studies with wider ranges of ketamine doses and behavioral tasks are needed to determine the presence and strength of potential behavioral effects.

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Motor expertise modulates the unconscious processing of human body postures

Experimental Brain Research ◽

10.1007/s00221-011-2788-7 ◽

2011 ◽

Vol 213 (4) ◽

pp. 383-391 ◽

Cited By ~ 23

Author(s):

Iris Güldenpenning ◽

Dirk Koester ◽

Wilfried Kunde ◽

Matthias Weigelt ◽

Thomas Schack

Keyword(s):

Human Body ◽

The Unconscious ◽

Unconscious Processing ◽

Body Postures ◽

Motor Expertise

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Differential Effects of Lowered Arousal on Covert and Overt Shifts of Attention

Journal of the International Neuropsychological Society ◽

10.1017/s1355617715000405 ◽

2015 ◽

Vol 21 (7) ◽

pp. 545-557 ◽

Cited By ~ 2

Author(s):

Bruno Fimm ◽

Klaus Willmes ◽

Will Spijkers

Keyword(s):

Sleep Deprivation ◽

Reaction Times ◽

Brain Structures ◽

Attentional Orienting ◽

Tight Coupling ◽

Attentional Processes ◽

Differential Effects ◽

Norepinephrine System ◽

Left And Right ◽

Healthy Participants

AbstractBased on previous studies demonstrating detrimental effects of reduced alertness on attentional orienting our study seeks to examine covert and overt attentional orienting in different arousal states. We hypothesized an attentional asymmetry with increasing reaction times to stimuli presented to the left visual field in a state of maximally reduced arousal. Eleven healthy participants underwent sleep deprivation and were examined repeatedly every 4 hr over 28 hr in total with two tasks measuring covert and overt orienting of attention. Contrary to our hypothesis, a reduction of arousal did not induce any asymmetry of overt orienting. Even in participants with profound and significant attentional asymmetries in covert orienting no substantial reaction time differences between left- and right-sided targets in the overt orienting task could be observed. This result is not in agreement with assumptions of a tight coupling of covert and overt attentional processes. In conclusion, we found differential effects of lowered arousal induced by sleep deprivation on covert and overt orienting of attention. This pattern of results points to a neuronal non-overlap of brain structures subserving these functions and a differential influence of the norepinephrine system on these modes of spatial attention. (JINS, 2015,21, 545–557)

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Central Visual Persistence as Measured by the Redundant Target Effect

Perception ◽

10.1068/v970242 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 259-259 ◽

Cited By ~ 1

Author(s):

C A Marzi ◽

G Nitro ◽

M Prior

Keyword(s):

Evoked Potential ◽

Normal Subjects ◽

Stimulus Onset ◽

Visual Persistence ◽

Single Stimulus ◽

Redundant Target ◽

Redundant Target Effect ◽

Speed Of Response ◽

Target Effect ◽

Onset Asynchrony

We measured the duration of central visual persistence by testing normal subjects for the redundant target effect (RTE), ie the speeding up of reaction time to redundant visual stimuli in comparison to similar single stimuli. Brief LED-generated flashes were presented to normal subjects either singly or in a pair at peripheral visual field locations (5 or 30 deg along the horizontal meridian). Stimulus pairs could appear either in the same hemifield at different locations or in opposite hemifields with a stimulus onset asynchrony (SOA) ranging between 0 and 100 ms. The subject's task was to press a key as soon as possible following the appearance of either a single stimulus or of the first stimulus in a pair. We found a robust and consistent overall RTE with double stimuli yielding faster RTs than single stimuli for both intrafield and interfield presentations. The effect decreased significantly from 0 ms to 40 ms SOA and at longer SOAs the speed of response to stimulus pairs was indistinguishable from that to a single stimulus. We believe that the longest SOA compatible with a reliable RTE (40 ms) reflects the duration of central persistence. Evoked-potential evidence gathered in our laboratory suggests that the locus of such persistence may be the extrastriate visual cortex.

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