Which phenomenon demonstrates the ability to respond to stimuli without conscious perception?

• A. Blindsight
• B. Hemisphere neglect
• C. Split-brain
• D. Thought alienation

Answer: (A)

The idea being tested is that you can respond to something without being consciously aware of it. Blindsight shows this clearly: after damage to the primary visual cortex, a person may report no vision in the affected field, yet can still respond accurately to visual cues in that field—guessing the location, detecting motion, or navigating around obstacles. That demonstrates nonconscious visual processing driving behavior, via alternative pathways (like routes through the superior colliculus) that don’t require conscious vision through the damaged cortex. This is why the phenomenon is the best answer.

The other options don’t illustrate this dissociation between awareness and action: neglect involves ignoring stimuli on one side despite perception; split-brain describes communication issues between the brain’s hemispheres; thought alienation isn’t a standard neuropsychological term for this phenomenon.