Psychology: Learning, Memory, and Cognition

The MCAT Psych/Soc section leans heavily on how organisms learn, how information is stored and retrieved, and how the mind reasons and errs. These topics reward clean vocabulary: know the exact terms, who the classic experimenters were, and the boundary between look-alike concepts. Master the distinctions below and a large block of predictable points becomes yours.

Core Idea

• Learning changes behavior through experience — classical conditioning (associating stimuli), operant conditioning (associating behavior with consequences), and observational learning (imitating a model).
• Memory is a three-stage system — sensory, short-term/working, and long-term — linked by the processes of encoding, storage, and retrieval.
• Cognition is how we solve problems and make decisions, often through fast, error-prone heuristics rather than slow, effortful analysis.

Classical Conditioning

Pavlov paired a bell with food until dogs salivated to the bell alone. Learn the four terms cold:

• Unconditioned stimulus (UCS): food — triggers a response with no learning.
• Unconditioned response (UCR): salivation to food — the natural, automatic reaction.
• Conditioned stimulus (CS): the bell — neutral until paired with the UCS.
• Conditioned response (CR): salivation to the bell alone — the learned reaction.

Key phenomena: acquisition (learning the pairing), extinction (CR fades when the CS is repeatedly presented without the UCS), spontaneous recovery (the CR briefly returns after a rest), generalization (similar stimuli trigger the CR), and discrimination (only the specific CS triggers it).

Operant Conditioning

Skinner showed that consequences shape voluntary behavior. Two dimensions combine:

• Reinforcement increases behavior; punishment decreases it.
• Positive means adding a stimulus; negative means removing one.

So positive reinforcement = add something pleasant (a treat); negative reinforcement = remove something unpleasant (taking painkiller to stop pain — this still increases the behavior). Positive punishment = add something aversive (a shock); negative punishment = remove something desirable (taking away a phone).

Reinforcement schedules control response rate and resistance to extinction:

• Fixed-ratio: reward after a set number of responses (rapid responding).
• Variable-ratio: reward after an unpredictable number — highest, steadiest response rate and hardest to extinguish (gambling/slot machines).
• Fixed-interval: reward after a set time (responding rises near the deadline).
• Variable-interval: reward after unpredictable time (slow, steady responding).

Observational Learning

Bandura's Bobo doll study showed children imitate aggression they watch modeled, without direct reinforcement. Learning occurs through modeling, guided by attention, retention, reproduction, and motivation, and is supported by mirror neurons. This bridges behaviorist and cognitive views.

Memory Systems and Processes

• Sensory memory: very brief, high-capacity (iconic ~visual, echoic ~auditory).
• Short-term/working memory: ~7 ± 2 items for ~15–30 seconds; working memory actively manipulates information (Baddeley's model).
• Long-term memory: effectively unlimited and durable.

Three processes move information: encoding (getting it in — deeper semantic encoding beats shallow), storage (keeping it), and retrieval (getting it out). Long-term memory splits into explicit/declarative (conscious — facts and events, tied to the hippocampus) versus implicit/nondeclarative (unconscious — skills and conditioned responses).

Forgetting: Ebbinghaus's forgetting curve shows rapid initial loss that levels off. Interference disrupts recall — proactive (old learning blocks new) versus retroactive (new learning blocks old).

Cognition, Intelligence, and Attention

Problem solving uses algorithms (guaranteed but slow) or heuristics (fast shortcuts). Common biases: availability (judging by ease of recall), representativeness (judging by resemblance to a prototype), and confirmation bias. Dual-process theory contrasts System 1 (fast, automatic, intuitive) with System 2 (slow, effortful, analytic). Attention includes selective attention (the cocktail-party effect) and divided attention. Language milestones and Whorf's linguistic relativity hypothesis appear briefly.

High-Yield Exam Patterns

• Expect a vignette asking you to label UCS/UCR/CS/CR — identify the naturally-occurring pair first, then the learned pair.
• Negative reinforcement is not punishment — it removes something bad to increase a behavior. This is the most tested trap.
• Variable-ratio is the schedule most resistant to extinction and drives gambling.
• Distinguish explicit vs implicit memory using the cue "conscious recall of a fact" (explicit) vs "skill or conditioned habit" (implicit).
• Match proactive vs retroactive interference by asking whether old or new information is doing the blocking.
• Availability and representativeness heuristics are frequent answer choices in reasoning/error questions.

Common Traps to Avoid

• Confusing negative reinforcement with punishment — both are easy to mislabel.
• Assuming extinction erases a memory; spontaneous recovery shows it does not.
• Swapping proactive and retroactive interference directions.
• Calling working memory the same as short-term memory — working memory actively manipulates, not just holds.
• Mixing up System 1 (intuitive) and System 2 (analytic) in dual-process questions.