MCAT Psychology/Sociology - Advanced Concepts

Front

Signal Detection Theory: d-prime and criterion (beta)

Back

d′ (d-prime) measures sensitivity—the separation between signal-plus-noise and noise-only distributions—and is independent of response bias. Criterion (β) reflects response bias; the prefrontal cortex helps modulate criterion, and basal ganglia circuitry is implicated in reward-based adjustments of criterion.

Front

Ventral vs Dorsal Visual Streams in Agnosia

Back

Ventral 'what' pathway (occipital to temporal) damage causes visual agnosia—inability to recognize objects despite intact vision. Dorsal 'where/how' pathway (occipital to parietal) damage causes optic ataxia—inability to reach for objects under visual guidance. Double dissociation proves functional independence of these streams.

Front

Place Theory vs Frequency Matching in Pitch Perception

Back

Place theory: pitch encoded by cochlear location of maximum displacement (tonotopic map). Problem: poor low-frequency resolution. Frequency matching (temporal theory): auditory nerve fires in phase with sound waves; volley principle allows neurons to fire in alternating patterns for frequencies above 500 Hz. Together, they explain the full hearing range.

Front

Proactive vs Retroactive Interference Mechanisms

Back

Proactive interference: old memories disrupt new learning (e.g., difficulty learning new phone number). Retroactive interference: new learning disrupts recall of old information (e.g., new password overwrites old one). Neurologically, proactive interference involves left ventrolateral prefrontal cortex; retroactive involves hippocampal unbinding during memory reconsolidation.

Front

Broca's vs Wernicke's Aphasia: Lesion Sites and Deficits

Back

Broca's aphasia (left inferior frontal gyrus): non-fluent speech, preserved comprehension, agrammatism, frustration awareness. Wernicke's aphasia (left superior temporal gyrus): fluent but nonsensical speech, impaired comprehension, anosognosia (unaware of deficit). The arcuate fasciculus connects them; its damage causes conduction aphasia (poor repetition, intact comprehension).