Appendix E: 50 Key Studies Summary

The landmark studies cited most frequently across this book, summarized with method, key finding, current status, and the chapter(s) where the study is discussed.

#	Study	Chapter	Method	Key Finding	Status
1	Harlow (1958) — Wire vs. cloth mother	15	Animal experiment	Infant rhesus monkeys preferred cloth surrogate mothers over wire mothers providing food; contact comfort drives attachment more than feeding	Well-replicated in animal models; ethical constraints limit direct human replication; foundational for attachment theory
2	Ainsworth et al. (1978) — Strange Situation	15	Observational assessment	Identified secure, anxious-ambivalent, and avoidant attachment patterns in infants based on response to separation and reunion	Foundational; extensively replicated; disorganized pattern added by Main & Solomon (1990)
3	Bowlby (1944, 1969–1980) — Attachment theory	15	Clinical observation + theory	Early attachment experiences form internal working models that shape relationship expectations across the lifespan	Clinical consensus; integrated with neuroscience and adult attachment research
4	Milgram (1963, 1974) — Obedience studies	37	Experiment	65% of participants administered maximum (potentially lethal) shocks when instructed by authority figure; compliance facilitated by graduated commitment, agentic state, and authority cues	Replicated in partial versions (Burger, 2009: similar compliance to 150V threshold); original methodology ethically prohibited; key findings robust
5	Asch (1951, 1955) — Conformity	35	Experiment	~75% of participants conformed to obviously incorrect group answers at least once; conformity reduced dramatically by single dissenter	Well-replicated; cross-cultural variations exist (higher conformity in collectivistic cultures)
6	Darley & Latané (1968) — Bystander effect	37	Experiment	In simulated emergency, help was less likely and slower when more bystanders were present; 85% helped when alone vs. 31% in 5-person group	Well-replicated; mechanisms (diffusion of responsibility, pluralistic ignorance) documented
7	Festinger & Carlsmith (1959) — Cognitive dissonance	4, 35	Experiment	Participants paid $1 (not $20) to lie showed more attitude change toward the task — insufficient justification produces dissonance-reducing attitude change	Classic; replicated with variations; some challenges to original interpretation
8	Loftus & Palmer (1974) — Memory reconstruction	5	Experiment	Leading questions ("smashed" vs. "contacted") altered estimates of car speed and later memory for glass; memory is reconstructive	Foundational; extensively replicated; applied to eyewitness testimony reform
9	Ebbinghaus (1885/1913) — Forgetting curve	5	Self-experiment	Memory decays rapidly after learning (50% forgotten within an hour); spaced repetition dramatically improves retention	Foundational; forgetting curve replicated across materials and populations
10	Kahneman & Tversky (1979) — Prospect theory	24	Decision experiments	Losses loom larger than equivalent gains; the value function is concave for gains and convex for losses (loss aversion coefficient ≈ 2)	Nobel Prize (2002); foundational to behavioral economics; extensively replicated
11	Tversky & Kahneman (1974) — Heuristics and biases	4	Experiments	Identified availability, representativeness, and anchoring-and-adjustment heuristics as sources of systematic judgment errors	Foundational to cognitive bias research; specific findings vary in replication; general framework robust
12	Deci & Ryan (1985–2000) — Self-Determination Theory	7, 22	Multiple methods	Autonomy, competence, and relatedness are universal psychological needs; their satisfaction predicts wellbeing across cultures and life domains	Extensive empirical support; cross-cultural validation; applied in education, health, and organizations
13	Dweck (1986, 2006) — Mindset	26	Experiments + longitudinal	Implicit beliefs about ability (fixed vs. growth) predict response to challenge, feedback, and failure; mindset can be changed through intervention	Foundational; some replication challenges (mindset interventions have mixed results at scale); core distinction robust
14	Steele & Aronson (1995) — Stereotype threat	36	Experiment	Black students performed worse than white students on difficult verbal items when race was made salient; performance equalized when race was not mentioned	Foundational; extensively replicated; meta-analyses confirm the effect; some debate about effect size in real-world conditions
15	Tajfel et al. (1971) — Minimal Group Paradigm	36	Experiment	Random, arbitrary categorization into groups (Klee vs. Kandinsky preference) produced in-group favoritism in resource allocation	Foundational for Social Identity Theory; cross-cultural replications; robust finding
16	Pettigrew & Tropp (2006) — Contact Hypothesis meta-analysis	36	Meta-analysis (515 studies)	Intergroup contact significantly reduces prejudice (d ≈ 0.45); effects are stronger under optimal conditions but present even without them	Foundational; most comprehensive quantitative assessment of the contact hypothesis
17	Greenwald, McGhee & Schwartz (1998) — IAT	36	Computer task	Implicit association test measures automatic associations between concepts; documents implicit racial, gender, and other associations inconsistent with explicit attitudes	Foundational; extensively used; debate about predictive validity for behavior (r ≈ .15 in meta-analyses); useful as group-level measure
18	Zajonc (1965) — Social facilitation	37	Experiment + review	Presence of others enhances performance of well-learned responses and impairs novel/complex ones; drive-arousal mechanism	Well-replicated; mechanism debate (evaluation apprehension vs. mere presence) ongoing
19	Latané, Williams & Harkins (1979) — Social loafing	37	Experiment	People exert less individual effort in groups (clapping, cheering, pulling rope); effect increases with group size	Well-replicated; reduced by identifiability and personal investment
20	Zimbardo (1971) — Stanford Prison Experiment	37	Experiment	Guards in simulated prison adopted abusive behaviors; study terminated after 6 days	Important historically; methodological critiques substantial (experimenter roles in escalation; demand characteristics; individual differences; selection bias); findings should be held with caution
21	Milgram (1974) — Obedience variations	37	Multiple experiments	Compliance reduced dramatically when authority was remote (telephone: ~20%), when peer dissented (10%), when victim was visible; compliance affected by situational elements	Generally replicated in partial replications
22	Sherif (1954) — Robbers Cave	36	Field experiment	Intergroup hostility produced by competition; reduced by superordinate goals requiring intergroup cooperation	Methodological concerns (Sherif manipulated results, destroyed contrary data); core finding re: superordinate goals supported by other research
23	Janis (1972, 1982) — Groupthink	37	Case study analysis	Historical analysis of foreign policy fiascos identified shared antecedents (cohesion, insulation, directive leadership) and symptoms	Influential framework; original historical analyses debated; experimental tests mixed; preventive structures well-supported
24	Ward et al. (2017) — Brain drain	39	Experiment	Mere presence of smartphone (face-down, notifications off) reduced working memory and fluid intelligence performance vs. phone in another room	Two-study RCT; direct experimental evidence; replicated in subsequent work
25	Markus & Kitayama (1991) — Self-construal	38	Theory + review	Distinction between independent (Western) and interdependent (East Asian) self-construals; implications for cognition, emotion, motivation	Foundational; most-cited paper in cultural psychology; cross-cultural studies confirm differential patterns
26	Henrich, Hein & Norenzayan (2010) — WEIRD	38	Review + analysis	Psychology research sample is dominated by WEIRD populations; WEIRD populations are outliers on many dimensions; generalizability of findings to global populations unknown	Foundational critique; landmark paper; shifted methodology in the field
27	Masuda & Nisbett (2001) — Holistic vs. analytic attention	38	Experiment	Japanese participants attended more to background context in scene descriptions; American participants attended more to focal objects	Well-replicated across multiple cognitive domains
28	Przybylski et al. (2013) — FOMO	39	Surveys	FOMO associated with lower need satisfaction (autonomy, competence, relatedness) and higher social media use	Well-designed scale development study; findings replicated
29	Orben & Przybylski (2019) — Screen time and wellbeing	39	Large-scale analysis	Association between screen time and adolescent wellbeing was very small (comparable to wearing glasses or eating potatoes)	Methodologically sophisticated; challenged on analytical choices by Haidt; debate ongoing; important counterpoint to extreme claims
30	Brady et al. (2017) — Moral-emotional content on Twitter	39	Computational analysis	Each moral-emotional word in a tweet associated with ~20% increase in retweet rate within ideological communities	Robust computational finding; demonstrates algorithmic amplification of outrage
31	Vaillant (2012) — Harvard Study of Adult Development	20, 40	Longitudinal (80+ years)	Warmth of relationships at age 50 predicted wellbeing at 80 better than any other variable including cholesterol	Most comprehensive longevity study; foundational for relationship-wellbeing connection
32	Gottman (1994) — Marital stability predictors	16, 18	Observational + longitudinal	Ratio of positive to negative interactions during conflict (5:1) predicts marital stability; identified Four Horsemen (criticism, contempt, defensiveness, stonewalling)	Well-supported by Gottman Institute research; some methodological debates; practically applicable
33	Seligman & Maier (1967) — Learned helplessness	10, 32	Animal experiment	Dogs exposed to uncontrollable shock later failed to escape controllable shock; learned that response and outcome are unrelated	Foundational; human analogs replicated; revised by Seligman to explanatory style model
34	Fredrickson (2001) — Broaden-and-build theory	6	Theory + experiments	Positive emotions broaden attentional and cognitive scope; build lasting resources; undone by negative emotions	Foundational; meta-analyses support broadening effect; building effect has more limited experimental evidence
35	Bandura (1977) — Self-efficacy	10	Theory + experiments	Belief in one's capacity for a specific behavior predicts approach vs. avoidance; domain-specific (not global)	Foundational; extensively replicated across education, health, and work domains
36	Neff (2003) — Self-compassion	10	Scale development + correlational	Self-compassion (self-kindness, common humanity, mindfulness) distinct from self-esteem; associated with wellbeing without the contingent fragility	Well-supported; self-compassion interventions show positive effects in clinical contexts
37	Latané & Darley (1970) — Decision tree for helping	37	Theory + experiments	Bystander intervention requires five sequential decisions; failure at any point prevents helping; identifies specific intervention points	Foundational; practical applications in safety and bystander intervention training
38	Erikson (1950) — Psychosocial stages	14	Theory + clinical observation	Eight stages of psychosocial development; each stage involves a central challenge; resolution affects all subsequent stages	Influential clinical framework; not experimentally derived; developmental stages supported by subsequent research
39	Kegan (1982, 1994) — Constructive-developmental theory	14	Theory + interview method	Adult development continues through socialized, self-authoring, and self-transforming mind stages; most adults don't reach self-authoring	Subject-Object Interview method; replicated in research settings; increasingly influential in leadership development
40	Berry (1997) — Acculturation strategies	38	Theory + cross-cultural research	Four acculturation strategies (integration, assimilation, separation, marginalization); integration associated with best outcomes; marginalization with worst	Foundational; replicated across many immigrant and bicultural populations
41	Walker & Avant (1983 / Worden 1991) — Tasks model of grief	34	Theory + clinical observation	Grief involves four tasks (acceptance, pain, adjustment, reinvestment) rather than stages; tasks can be worked sequentially or revisited	Clinically influential; practically applied; does not claim to be predictive of all grief trajectories
42	Gelfand et al. (2011) — Tight/loose cultures	38	Cross-national survey (33 nations)	Tight cultures (strong norms, low deviance tolerance) vs. loose cultures (weak norms, high deviance tolerance); dimension predicts coordinated social behavior	Foundational 33-nation study; replicated; applied in organizational and cross-cultural research
43	Edmondson (1999) — Psychological safety	25, 37	Survey + observational	Psychological safety predicts team learning behavior; higher psychological safety = more reporting of errors and questions	Foundational; Google's Project Aristotle (2016) independently confirmed as strongest team predictor; extensively applied
44	McGuire (1964) — Inoculation theory	35	Experiment	Weakened arguments + refutation produced resistance to later stronger attacks; immunological metaphor	Classic; contemporary applications to misinformation resistance confirmed by Compton et al. (2021) meta-analysis
45	Petty & Cacioppo (1986) — Elaboration Likelihood Model	35	Experiments + theory	Dual-route model of persuasion (central vs. peripheral); durability and reliability of attitude change depends on route	Foundational; extensively replicated; integrated with Chaiken's Heuristic-Systematic Model
46	Galton (1907) — Wisdom of crowds	37	Observational	Crowd's average estimate of ox weight was more accurate than most individual expert estimates	Foundational; extensively extended by Surowiecki; conditions for collective intelligence documented
47	Walker (1989) — Sleep architecture	30	Neuroimaging + polysomnography	Sleep architecture involves characteristic cycles of NREM and REM stages; different stages serve different memory consolidation functions	Foundational for sleep science; memory consolidation during sleep well-replicated
48	Tervalon & Murray-García (1998) — Cultural humility	38	Conceptual/clinical	Cultural humility (ongoing self-reflection, recognition of power dynamics) as alternative to cultural competency (endpoint achievement)	Foundational clinical framework; widely adopted in healthcare and social work training
49	Cowan et al. (2007) — Working memory capacity	5, 39	Experimental	Working memory capacity ≈ 4 chunks of information; severely limited; interference from irrelevant information reduces effective capacity	Strong experimental basis; applied to education and cognitive load design
50	Frankl (1946/2006) — Meaning and extreme conditions	11, 40	Autobiography + clinical observation	Finding meaning in suffering is possible under extreme conditions; humans can transcend circumstances through the freedom of inner response	Clinical framework, not experimental; logotherapy applications; Viktor Frankl Institute provides current research applications

Note on study status: Psychology is in an ongoing process of evaluating replication across its landmark findings. "Well-replicated" means the core finding has been reproduced by independent labs in multiple samples. "Mixed replication" means some attempts succeeded and others failed — suggesting the effect is real but context-dependent. "Methodological concerns" means the original study had flaws that limit interpretation, though the phenomenon it pointed to may still be real. All findings should be held with appropriate epistemic humility.