Hassett Case Study

background

observed children with CAH (Congenital adrenal hyperplasia; condition exposed to higher than normal levels of prenatal androgens → male sex hormones) where girls showed preference for stereotypical male toys compared to unaffected females, theorized toy preferences are shaped by hormones & NOT socialization, observed significant sex differences matching those seen in humans & concluded differences stem from prenatal hormone exposure

aims/hypothesis

(1) to test if sex differences in children’s toy preferences result from biological factors (prenatal hormone exposure) rather than through socialization, (2) to investigate if male & female monkeys have similar toy preferences to human infants despite no human socialization experience with human toys

research methodology

IMD → 2 groups of monkeys were compared (male & female), laboratory experiment → conducted in outdoor enclosure but had controlled variables

participant sample

opportunity sample, 135 rhesus monkeys at Yerkes National Private Researh Center Field Station, 14 monkeys already participated in research so NOT included in study, 39 babies not included (difficult to identify sex), remaining 82 (61 females & 21 males) used in study → only 34 interacted with toys (23 females & 11 males) so included in analysis

psychology being investigated

play → types of play seen at different developmental stages / sex differences & role of nature → biological sex determined by sex chromosomes & determines level or hormonesso causes brain differences / socialization & role of nature → gender is individual’s personal sense of masculinity/femininity so children learn by gender/societal expectations

IV’s and DV’s

IV: sex of the monkeys / DV: whether monkeys interacted with plush or wheeled toys / social rank (determined by grooming behavior) and age were recorded

procedures

seven 25 min trials complete in outdoor area of outside enclosure, (before) positioned pairs of toys (one wheeled, one plush) in outdoor area while monkeys waited indoors → toys placed 10 meters apart & positions counterbalanced to prevent area preferences, toys varied in size shape color, wheeled toys: wagons, truck, car, construction vehicle, shopping cart, dump truck → 2 observers watched videos & used behavioral checklist for interactions (extended manipulation, holding, sitting on, dragging, carrying, sniffing, mouthing, destroying, throwing, jumping away from), ambiguous behaviors discussed, monkey’s age sex & rank recorded with every interaction

equipment/material used

handobs app, recorded data using palm pilots

results (quantitative data)

females did not play w/ wheeled toys as much as males (1.27 min: F, 4.76 min: M), females played with plush toys longer than males (1.49 min: F, .53 min: M), males played with wheeled toys significantly longer than plush (standard deviation for duration relatively large compared to females, SD 7.59: M, SD 2.2: F), females showed greater individual differences in time spent engaged in plush toy play, significant positive correlation between social rank & frequency of interaction for both types of toys → higher rank monkeys interacted more w/ toys, higher rank females spent more time interacting w/plush toys but not wheeled toys, observers calculated average frequencies & durations for each behavior (monkeys w/ fewer than 5 behaviors discarded → 3males & 14 females) → male plush mean: 2.06 / female plush mean: 7.97, male wheeled mean: 9.77, female wheeled mean: 6.96

results (qualitative data)

n/a

conclusions

sex-typed toy preferences in humans may result from biological sex differences since monkeys show similar preferences to infants without socialization, human toy preferences reflect hormonally influenced behavior & cognitive biases, female show some preference for plush toys (females w/ NO preference ranked lower in social hiearchy), no significant difference between males & females in terms of frequency of wheeled toy play, malemonkeys significantly prefer wheeled toy play, males play less w/ plush toys than females, most monkeys did not interact with toys at all

strengths

use of large amounts of data collection (7 separate 25-min trials, 2050 hrs of data collection), use of video cameras (humans remained outside of enclosure → no EV, videos can be rewatched as needed, machines do not lie)

weaknesses

standardized procedure abandoned on one trial (one monkey ripped apart a plush toy → terminated 7 min early), lack of adult males → 11 male monkeys either all juvenile, subadult, or elderly → toy pref might be influenced by social rank and age, conducted with monkeys living in captivity only → lack of predators reduces ecological validity

situational & individual explanations

individual: some monkeys were not used in thef final data analyses as they showed little to NO interest in toys / situational: monkeys were placed in scenarios that encouraged toys

nature vs nurture

nature: hassett believed toy preferences in humans may be due to nature & caused by biological not learned difference / nurture: fdinings support the role of nurture in toy preference → interactions affected by social rank

generalizability

(weakness) lack of adult male monkeys in sample → 11 male monkeys were all either juvenile/subadult/elderly, (weakness) toy/play interaction may be affected by social rank, (weakness) study conducted w/ monkeys living in captivity → may show greater interest due to lack of predators

reliability

(strength) well-operationalized behavioral checklist→ gave a behavior & clear description → improved inter-observer reliability

validity

(strength) 7 separate 25-min trials → diff pairsof plush & wheeled toys with counterbalanced placements → showed real preference for a wheeled toy or plush rather than for particular color/size, (strength) use of video cameras rather than having observers present → reduces demand characteristics and altered monkey behavior; monkeys may have expected reward

application

suggests gender specific toy preferences may be result of biological factors & not socialization → makes some play activities more appealing, parents & educators & developmental studies may assist in gender specific/neutral play in children

ethics

(strength) followed NIH guide for the care and use of laboratory animals → ensured priority of treatment & wellbeing of animals being studied, (strength) housed in usual social groups in outdoor enclosure with regulated temp indoor area & constant access to food and water