Transcranial magnetic stimulation to visual cortex induces suboptimal introspection.

Area of Science:

• Neuroscience
• Cognitive Science
• Psychology

Background:

• Blindsight patients exhibit impaired conscious visual experience despite intact visual discrimination.
• Studying subjective awareness requires separating it from objective performance.
• Transcranial magnetic stimulation (TMS) offers a method to induce blindsight-like phenomena in neurologically intact individuals.

Purpose of the Study:

• To investigate whether TMS-induced blindsight in healthy observers is due to reporting biases or genuine metacognitive deficits.
• To explore the role of internal statistical models in metacognitive judgments and awareness.

Main Methods:

• Utilized a criterion-free method to assess performance and awareness.
• Applied TMS to the visual cortex of neurologically intact participants.
• Compared metacognitive judgments under TMS with previous findings under visual masking.

Main Results:

• TMS-induced blindsight was conclusively differentiated from reporting biases.
• Participants under TMS exhibited suboptimal metacognitive judgments, indicating a loss of awareness.
• Introspective judgments were optimal under visual masking but suboptimal under TMS.

Conclusions:

• TMS can induce a state of metacognitive blindness, mimicking actual blindsight.
• Metacognitive judgments rely on the validity of internal perceptual models.
• External perturbations, like TMS, can disrupt these models, leading to introspective suboptimality.