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Correlational findings

Study Robinson et al. (2001): study US 1986

Public
Toddlers, same-sex twins, Colorado, United States, followed from 14 to 24 months of age, 1986-1989
Survey name
Unnamed study
Sample
Respondents
N = 400
Non Response
Assessment
Behavioural observation
behavioral observation at home and in laboratory, recorded on video tape; parental reports in questionnaire

Correlate

Authors's Label
Stability of positive hedonic tone across situations
Our Classification
Remarks
in both test situations the positive Hedonic Tone Scale was used (Easterbrooks & Emde, 1083); Bayley: 40-45 min period, rating in 1-min intervals, sampled in 5-min blocks (i.e. 5 min on, 5 min off) Free play: 15 min period, rated continuously, 30 sec intervals
Distribution
- at age 14 month:  Bayley: M=2.41 sd=.33 N=393  Free play: M=2.23 sd=.27 N=394
- at age 20 month:  Bayley: M=2.44 sd=.31 N=367  Free play: M=2.30 sd=.28 N=369
at age 24 month:  Bayley: M=2.50 sd=.34 N=354  Free play: M=2.25 sd=.22 N=354
Operationalization
Rating from behavior recorded on video tape:

A: During BAYLEY TEST:
- completed 30 min after experimenter arrived at the home
- test consists of a give-and-take between the child seated in a chair and a female experimenter
- child is presented a toy
- an action is modeled
- child responses
- toy is removed
- a new toy is presented
- Experimenter maintains a posivitve, animating tone.

B: During FREE PLAY SITUATION
- 2 hours after experimenters have arrived at the home
- standard set of 10 toys is arranged on floor
- mother sits in chair, allowed to respond but not to initiate
- both twins play freely while being filmed

Rating scale:
1 no positive emotion observed
2 positive interest
3 smiling
4 strong laughter

Observed Relation with Happiness

Happiness Measure Statistics Elaboration / Remarks A-CA-mi-tsb-v-4-a r = +.34 p < .01 at age 14 months (N=368) A-CA-mi-tsb-v-4-a r = +.37 p < .01 at age 20 months (N=343) A-CA-mi-tsb-v-4-a r = +.25 p < .01 at age 24 months (N=356)