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Psychology Unit 2: Cognition

Cognition covers how we perceive, think, solve problems, remember and measure intelligence, including the shortcuts and biases that lead us astray.

Covers: Perception, thinking, problem solving and biases, memory processes, forgetting, intelligence and testing

Study guide

Perception is how the brain organizes and interprets sensations. Bottom-up processing starts with sensory input, while top-down processing uses expectations and experience; perceptual sets and context shape what we notice, and selective attention and inattentional blindness show how much we miss. Gestalt principles (figure-ground, proximity, similarity, closure) describe how we group information. Depth perception uses binocular cues like retinal disparity and monocular cues like relative size, linear perspective and interposition, and perceptual constancies keep objects stable as conditions change.

Thinking uses concepts and prototypes. We solve problems with algorithms (step-by-step procedures) or heuristics (mental shortcuts). Heuristics can mislead: the availability heuristic judges likelihood by how easily examples come to mind, and the representativeness heuristic judges by resemblance to a prototype. Other biases include confirmation bias, functional fixedness, mental sets, framing, anchoring and overconfidence. Creativity involves divergent thinking.

Memory involves encoding, storage and retrieval. The multi-store model describes sensory memory, short-term (working) memory with limited capacity, and long-term memory. Long-term memories are explicit (episodic and semantic) or implicit (procedural and conditioned). Encoding improves with deep processing, chunking, mnemonics, the spacing effect and the testing effect. Retrieval is helped by cues and context; the serial position effect favors the first and last items. Forgetting happens through encoding failure, decay, and proactive and retroactive interference, and memories can be reconstructed and distorted, as in the misinformation effect. Amnesia may be anterograde (can't form new memories) or retrograde (losing past ones).

Intelligence theories include Spearman's general intelligence (g), Gardner's multiple intelligences and Sternberg's triarchic theory. Good tests are standardized, reliable (consistent) and valid (measure what they claim). Achievement tests measure what you've learned, and aptitude tests predict future performance. Scores follow a normal curve, and the Flynn effect shows rising scores over time. Stereotype threat can lower performance.

Binet created the first intelligence test to identify French schoolchildren who needed extra help, using the idea of mental age. Modern IQ tests set the average score at 100 with a standard deviation of 15, so about 68% of people score between 85 and 115. Construct validity asks whether a test measures the trait it claims to measure. Predictive validity asks whether scores predict later performance, as when entrance-test scores predict college grades. Reliability can be checked by test-retest (same results over time) or split-half (two halves of the test agree).

Benjamin Whorf's linguistic relativity hypothesis says the language we speak shapes how we think. Today most researchers accept a weaker version, in which language influences thought but doesn't strictly limit it. Working memory, in Baddeley's model, is an active workspace with limited capacity (short-term memory holds roughly 7 ± 2 items), with a central executive, a phonological loop and a visuospatial sketchpad. Long-term potentiation, the strengthening of synapses with repeated use, is the neural basis of memory.

Key ideas

• Perception combines bottom-up input with top-down expectations.
• Heuristics are efficient shortcuts that can produce biases.
• Memory involves encoding, storage and retrieval, and it's reconstructive.
• Spacing, testing and deep processing improve learning.
• Good intelligence tests are standardized, reliable and valid.

Formulas and rules

Common mistakes

• Confusing proactive and retroactive interference.
• Thinking a reliable test must be valid; it can be consistent but measure the wrong thing.

Words to know

Bottom-up processing

Perception that starts with sensory input.

Top-down processing

Perception guided by expectations and experience.

Perceptual set

A mental predisposition to perceive one thing over another.

Inattentional blindness

Failing to notice visible objects when attention is elsewhere.

Gestalt

The tendency to organize parts into meaningful wholes.

Retinal disparity

A binocular depth cue from the slight difference between the eyes' images.

Algorithm

A step-by-step procedure that guarantees a solution.

Heuristic

A mental shortcut for judgments and problem solving.

Availability heuristic

Judging likelihood by how easily examples come to mind.

Representativeness heuristic

Judging by how well something matches a prototype.

Confirmation bias

Seeking information that supports what you already believe.

Functional fixedness

Seeing objects only in their usual functions.

Encoding

Getting information into memory.

Working memory

Active short-term processing of information.

Episodic memory

Memory of personal experiences.

Semantic memory

Memory of facts and general knowledge.

Procedural memory

Implicit memory for skills and how to do things.

Chunking

Grouping information into meaningful units.

Spacing effect

Spread-out study improves long-term retention.

Testing effect

Retrieval practice improves memory.

Serial position effect

Better recall of the first and last items in a list.

Retroactive interference

New learning disrupts recall of old information.

Misinformation effect

Misleading information distorts a memory.

Anterograde amnesia

Inability to form new memories.

Reliability

A test's consistency.

Validity

Whether a test measures what it claims to.

Sample practice questions

5 more questions like these, from level 1 to 5, are in the practice set.