Memory and Cognition Distinctions

Short-Term vs. Working Memory

• Short-term memory. Traditional term - temporary storage for ~20-30 seconds, ~7 ± 2 items.
• Working memory. The more modern concept - Baddeley’s multi-component model including phonological loop, visuospatial sketchpad, central executive, and episodic buffer. Actively PROCESSES info, not just holds it.

Key distinction: STM is passive storage. Working memory is active manipulation. In practice, MCAT uses both terms loosely but working memory is the current preferred framework.

Iconic vs. Echoic Memory

• Iconic. VISUAL sensory memory. Lasts ~0.5 seconds. Sperling’s grid experiment.
• Echoic. AUDITORY sensory memory. Lasts ~3-4 seconds. Why you can “replay” what someone just said to you.

Key distinction: iconic = eyes (brief). Echoic = ears (longer). Both are raw sensory memory before attention selects what to pass on.

Explicit vs. Implicit Memory

• Explicit (declarative). Memories you can consciously DESCRIBE. Episodic + semantic.
• Implicit (non-declarative). Memories that influence behavior without conscious recall. Procedural (bike riding), priming, conditioning.

Key distinction: can you verbalize it? Yes = explicit. No but still shapes behavior = implicit.

Episodic vs. Semantic vs. Procedural Memory

• Episodic. Autobiographical events. “My 18th birthday.” Explicit.
• Semantic. General knowledge and facts. “Paris is in France.” Explicit.
• Procedural. How to do things. “Riding a bike.” Implicit. Stored in basal ganglia + cerebellum.

Key distinction: episodic = personal events. Semantic = general facts. Procedural = motor skills. First two are explicit; last is implicit.

Retrograde vs. Anterograde Amnesia

• Retrograde. Loss of memories BEFORE the injury. “Retro = back.”
• Anterograde. Inability to form NEW memories AFTER the injury. “Antero = forward.”

Key distinction: direction of memory loss. Hippocampus damage → anterograde (can’t make new). Concussion often → retrograde (loses recent).

Proactive vs. Retroactive Interference

• Proactive. OLD info disrupts NEW learning. Old password keeps interfering with new one.
• Retroactive. NEW info disrupts OLD memory. New address makes old address harder to recall.

Key distinction: proactive “pushes forward” from old. Retroactive “reaches back” into old. Same direction as the prefixes.

Alzheimer’s vs. Korsakoff’s Syndrome

• Alzheimer’s. Progressive. Amyloid plaques + tau tangles. Short-term memory affected first. Cholinergic neuron loss → cholinesterase inhibitors help.
• Korsakoff’s. Caused by thiamine (B1) deficiency, usually chronic alcoholism. Preceded by Wernicke’s encephalopathy. Severe memory loss with CONFABULATION (making up stories). Not progressive if treated.

Key distinction: Alzheimer’s progresses. Korsakoff’s can stabilize with thiamine. Alzheimer’s has plaques/tangles; Korsakoff’s has vitamin deficiency. Korsakoff’s signature: confabulation.

Dementia vs. Delirium

• Dementia. Gradual, progressive cognitive decline. Alzheimer’s, vascular dementia, Lewy body dementia.
• Delirium. Acute, sudden, often reversible confusion. Triggered by infection, medication, drug withdrawal, metabolic issues.

Key distinction: dementia = slow, lasting. Delirium = fast, often reversible. Elderly patients with acute confusion in a hospital are almost always delirious, not newly demented.

Serial Position Effect: Primacy vs. Recency

• Primacy. Better recall of items EARLY in a list. They had more rehearsal time → moved to LTM.
• Recency. Better recall of items LATE in a list. Still in working memory.

Key distinction: primacy = LTM mechanism. Recency = working memory mechanism. A delay between list and recall wipes out recency (still working memory) but not primacy (already in LTM).

Assimilation vs. Accommodation (Piaget)

• Assimilation. Fitting new info into EXISTING schema. Child sees a wolf, calls it a “dog” (fits into dog schema).
• Accommodation. MODIFYING schemas to fit new info. Child learns “that’s a different kind of animal called a wolf” (splits schema).

Key distinction: assimilation keeps schema. Accommodation changes schema. Both happen constantly as children (and adults) learn.

Availability vs. Representativeness Heuristic

• Availability. Judging probability by how easily EXAMPLES come to mind. “Plane crashes seem scary because of news coverage.”
• Representativeness. Judging probability by how well something matches a PROTOTYPE. “Linda sounds like a feminist, so she’s probably a feminist bank teller” (conjunction fallacy).

Key distinction: availability uses specific memories. Representativeness uses category match. Availability = “I can think of examples.” Representativeness = “It fits the type.”

Fluid vs. Crystallized Intelligence

• Fluid. Abstract reasoning on NOVEL problems. Peaks in early adulthood, then DECLINES.
• Crystallized. Accumulated knowledge, vocabulary, experience. STABLE or IMPROVES through middle age.

Key distinction: fluid declines; crystallized doesn’t. Older adults compensate by using crystallized knowledge to offset fluid decline.

Broca’s vs. Wernicke’s Aphasia

• Broca’s (nonfluent/expressive). Frontal lobe lesion. Labored, broken speech. Comprehension PRESERVED. Patient often frustrated because they know what they want to say.
• Wernicke’s (fluent/receptive). Temporal lobe lesion. Fluent but NONSENSICAL speech (“word salad”). Comprehension IMPAIRED. Patient often unaware their speech doesn’t make sense.

Key distinction: Broca’s = Broken speech, understanding intact. Wernicke’s = fluent nonsense, understanding wrecked. Mnemonic: “Broca’s is Broken; Wernicke’s is Wacky.”

Conduction vs. Global Aphasia

• Conduction aphasia. Damage to ARCUATE FASCICULUS (connecting Wernicke’s to Broca’s). Speech fluent, comprehension OK, but CAN’T REPEAT what they just heard.
• Global aphasia. BOTH Broca’s and Wernicke’s damaged. Severely impaired production and comprehension.

Key distinction: conduction = production and comprehension work, but repetition fails. Global = everything impaired.

Linguistic Relativism vs. Determinism

• Relativism (weak Whorfian). Language INFLUENCES thought (makes some thoughts easier or more habitual).
• Determinism (strong Whorfian). Language DETERMINES thought (you can’t think concepts you don’t have words for).

Key distinction: relativism = language nudges thought. Determinism = language forces thought. Modern linguists accept relativism but reject strong determinism.

Nativist vs. Learning vs. Interactionist (Language Development)

• Nativist (Chomsky). Children born with a Language Acquisition Device. Language is innate.
• Learning (Skinner). Language acquired through imitation + reinforcement. Environmental only.
• Interactionist (Vygotsky). Both biology AND social interaction needed. Children are built to learn, and social interaction activates that capacity.

Key distinction: nativist = nature. Learning = nurture. Interactionist = both. Most modern researchers lean toward interactionist.