IB Psych SL Studies

• Aim: Investigate role of hippocampus in memory formation.

• Procedure: Case study of HM, who had bilateral medial temporal lobectomy (hippocampus removed) to treat severe epilepsy. Tested using memory tasks including mirror-drawing.

• Results: Suffered anterograde amnesia—could not form new episodic or semantic memories. Procedural memory intact; he improved at mirror-drawing despite no conscious memory of practice.

• Conclusion/Link: Hippocampus is critical for consolidating explicit (declarative) memories but not implicit (procedural) memories. Supports separation of memory systems

HM: Milner (1966)

• Aim: Whether learning a new skill changes brain structure.

• Procedure: 24 non-jugglers had baseline MRI. 12 learned to juggle (3-ball cascade) for 3 months. Second MRI taken. After 3 more months of not juggling, third MRI taken. Control group had no training.

• Results: Juggling group showed significant grey matter expansion in mid-temporal area (MT/V5) at second scan. This decreased again after they stopped juggling. Control group showed no change.

• Conclusion/Link: Brain structure changes in response to environmental demands. Demonstrates neuroplasticity—both expansion from learning and reduction after stopping.

Draganski et al. (2004)

• Aim: Role of acetylcholine in spatial memory formation.

• Procedure: Rats learned a Hebb-Williams maze. Experimental group injected with scopolamine (blocks acetylcholine receptors). Control group injected with saline. Both groups' speed and errors recorded.

• Results: Scopolamine group took significantly longer to learn the maze and made more errors than controls.

• Conclusion/Link: Acetylcholine plays a key role in consolidation of spatial memory. Blocking it impairs encoding.

Rogers & Kesner (2003)

• Aim: Effect of high cortisol levels on explicit verbal memory.

• Procedure: Double-blind, placebo-controlled experiment. 51 healthy participants received either high-dose cortisol (160mg/day), low-dose (40mg/day), or placebo for 4 days. Tested on verbal declarative memory task (recall of prose passage).

• Results: High-dose group performed significantly worse on memory recall than low-dose and placebo groups. Performance returned to normal after treatment stopped—effect was reversible.

• Conclusion/Link: Elevated cortisol (mimicking chronic stress) impairs explicit verbal memory retrieval. Links stress hormones to cognitive function.

Newcomer et al. (1999)

• Aim: Whether MHC genes influence mate preference through body odor.

• Procedure: 44 male students wore a t-shirt for 2 nights. 49 female students rated smell of 7 t-shirts (3 MHC-similar, 3 MHC-dissimilar, 1 unworn control) for pleasantness and sexiness.

• Results: Women rated MHC-dissimilar shirts as more pleasant and sexier. Pattern reversed in women taking oral contraceptives—they preferred MHC-similar.

• Conclusion/Link: Body odor conveys information about immune system genetics. Preference for dissimilar MHC may promote offspring with stronger immune systems. Supports biological basis for human attraction.

Wedekind (1995)

• Aim: Relative contribution of genetics vs. environment to body weight.

• Procedure: Large-scale twin study using medical records. Compared concordance rates for BMI between MZ and DZ twins, including pairs reared together and apart.

• Results: MZ twins had significantly higher BMI concordance than DZ twins, regardless of whether raised together or apart. Shared environment had minimal effect on MZ weight similarity.

• Conclusion/Link: Genetics play a major role in determining body weight. Supports nature side of nature vs. nurture debate.

Sorensen et al. (1992)

• Aim: Effect of schema on memory encoding and retrieval.

• Procedure: 30 participants individually waited in a room arranged as an office (contained schema-consistent items like desk, and inconsistent items like a skull). After leaving, asked to recall everything in the room.

• Results: High recall for schema-consistent objects. Schema-inconsistent items either very well recalled (skull) or poorly (picnic basket). Many falsely recalled books—objects not present but consistent with office schema.

• Conclusion/Link: Memory is reconstructive. Schemas guide encoding and retrieval; we fill gaps with schema-based expectations. Explains memory distortions.

Brewers & Treyens (1981)

• Aim: How framing options as gains or losses affects decision-making.

• Procedure: Participants given "Asian Disease" problem: 600 people expected to die. Choose between sure option and gamble, mathematically identical but framed as number of lives saved (gain) or lost (loss).

• Results: In gain frame (lives saved), 72% chose sure option (risk-averse). In loss frame (lives lost), 78% chose gamble (risk-seeking).

• Conclusion/Link: People are not purely rational. Framing of information systematically biases decisions, violating expected utility theory.

Tversky & Kahneman (1986)

• Aim: Whether leading questions distort eyewitness memory.

• Procedure: Exp 1: Watched car crash film. Asked "How fast were cars going when they ___ each other?" with verbs: smashed, collided, bumped, hit, contacted. Exp 2: One week later, "smashed" and "hit" groups asked if they saw broken glass (there was none).

• Results: Exp 1: Higher speed estimates for more intense verbs (smashed = 40.8mph; contacted = 31.8mph). Exp 2: "Smashed" group over twice as likely to falsely report broken glass.

• Conclusion/Link: Post-event information (leading question verb) alters original memory. Memory is reconstructive and vulnerable to distortion.

Loftus & Palmer (1974)

• Aim: Test effect of articulatory suppression on phonological loop.

• Procedure: Both groups saw list of 7 consonant letters for 5 seconds, then recalled in serial order. Experimental group had to repeat "1, 2" aloud during presentation (articulatory suppression). Control group saw list in silence.

• Results: Articulatory suppression group recalled significantly fewer letters correctly than controls.

• Conclusion/Link: Articulatory suppression prevents subvocal rehearsal in phonological loop, disrupting recall. Supports Baddeley's Working Memory Model.

Landry & Bartling (2011)

• Aim: Accuracy and confidence of flashbulb memories over time.

• Procedure: 106 students completed questionnaire on circumstances of learning about Challenger disaster (who with, where, doing what) within 24 hours. 44 same students completed same questionnaire 2.5 years later. Rated confidence on 1-5 scale.

• Results: Only 3% perfectly matched original; 25% completely wrong on all details. Mean confidence rating was 4.17/5 despite inaccuracy. High confidence uncorrelated with accuracy.

• Conclusion/Link: Flashbulb memories are not more accurate than ordinary memories despite high subjective confidence. Challenges theory of special mechanism for flashbulb memories.

Neisser & Harsch (1992)

• Aim: Test minimal conditions for intergroup discrimination.

• Procedure: 14-15 year old boys randomly assigned to groups based on supposed painting preference (Klee or Kandinsky). Individually allocated points to anonymous in-group and out-group members using matrices. Could choose fair distribution, maximum joint profit, or maximum difference favoring in-group.

• Results: Boys consistently favored in-group over out-group. Often chose maximum difference strategy—sacrificing total group profit to make out-group worse off relative to in-group.

• Conclusion/Link: Mere categorization into groups (even meaningless ones) causes in-group favoritism and out-group discrimination. Supports Social Identity Theory.

Tajfel (1971)

• Aim: Whether children imitate observed aggressive behavior without reinforcement.

• Procedure: 36 boys and 36 girls (3-6 years). One group watched adult model behave aggressively toward Bobo doll (hitting, kicking, verbal aggression); control saw non-aggressive model or no model. Children then placed in room with Bobo and observed through one-way mirror.

• Results: Children exposed to aggressive model imitated specific aggressive acts significantly more than controls. Boys more physically aggressive; girls more verbally aggressive. Greater imitation when model was same sex.

• Conclusion/Link: Aggression can be learned through observation and imitation alone, without direct reinforcement. Supports Social Learning Theory.

Bandura (1961)

• Aim: Whether culture/ecology influences conformity rates.

• Procedure: Temne (collectivist, rice-farming, Sierra Leone), Inuit (individualist, hunting, Canada), and Scottish controls completed adapted Asch line-judgment task measuring conformity.

• Results: Temne showed highest conformity (collectivist, agricultural). Inuit showed lowest conformity (individualist, hunting)—even lower than Scots. Differences aligned with cultural values and subsistence methods.

• Conclusion/Link: Cultural norms and ecological demands shape degree of conformity. Collectivist farming societies value conformity; individualist hunting societies value independence.

Berry (1967)

• Aim: How parents directly reinforce gender-stereotypical behavior.

• Procedure: Naturalistic observation of 24 families (12 with boys, 12 with girls) in their homes. Observers coded 46 child behaviors and 19 parent reactions over 5-week period.

• Results: Girls received positive reinforcement for playing with dolls, dressing up, asking for help. Boys reinforced for block play and large motor activities. Parents actively discouraged cross-gender behavior in boys.

• Conclusion/Link: Gender-role behaviors are directly taught and reinforced by parents in daily interactions. Demonstrates enculturation of gender norms.

Fagot (1978)

• Aim: Predictors of acculturative stress in elderly Asian-American immigrants.

• Procedure: Structured interview survey with nationally representative sample of 2,095 Asian Americans aged 60+. Measured acculturation level (English proficiency, media use, ethnic identity), discrimination experiences, social support, and depression/anxiety.

• Results: Approximately 40% showed depression symptoms. Strongest predictors of stress: perception of discrimination, low social support from family/friends. Paradoxically, high English proficiency also linked to stress (greater exposure to discrimination). Strong ethnic identity and family bonds protective.

• Conclusion/Link: Acculturative stress significantly impacts immigrant mental health. Experience of discrimination is a key factor. Supports Berry's acculturation framework—integration strategy reduces but does not eliminate stress.

Lueck & Wilson (2010)