Overview of study: Toddlerhood marks the beginning of independent locomotion and exploration, and during this time parents provide important scaffolding for affective learning (i.e., learning about the emotional value, safety vs. danger, of stimuli). Here, a within-subjects experimental design investigated whether mere parental presence (versus absence) influenced reward learning in toddlerhood. Study 1 examined the effect of social context on toddlers’ (N=88; mean age = 31.8 months) reward learning in a classical conditioning paradigm. Learning was assessed using a T-maze preference test. Although there was no main effect of social context on reward learning, social context did interact with age to influence learning, such that parental presence was more likely to increase behavioral preferences for conditioned stimuli in older toddlers. Because these differences could have been the result of age-related confounds, Study 2 asked whether changes in task design could better reveal parental influences on reward learning in younger toddlers. In a slightly younger sample (N = 44; mean age = 29.6 months), we observed evidence of parental influence if toddlers were conditioned in the absence of their parent first (i.e., the task order mattered). Taken together, these data indicate that classical reward conditioning during the toddler period is indirectly influenced by parental presence/absence under particular circumstances (i.e., age and order).
Study 1 Methods:
Schematic of Study 1 design: Conditioning and testing paradigm. A. Conditioning Phase: During conditioning, toddlers were presented with stimuli on a computer screen. For each condition, toddlers sat next to a teacher and experimenter. For the Parent Close condition, the parent was also seated next to the toddler; for the Parent Far condition, the parent sat far behind the toddler. B. Recall Test (T-maze): Following the conditioning phase, toddlers were brought to a play tent where, sitting in their teacher’s lap, the teacher pointed to both of the doors (left and then right) and told the toddler that behind each shape was the same prize (e.g., a sticker/small toy, shown as an example on the first trial). The toddler was prompted to choose from which door they wanted to retrieve their prize. The teacher then helped them retrieve the prize through the door. Each toddler completed 5 randomized trials before returning to the computer. C. Recall Test: Toddlers were shown both shapes, side-by-side, and asked which shape was their favorite. Toddlers then completed the next condition (parent or teacher). Order of parental context was randomized between participants.
Statistical Model:
Recall test (T-maze preferences) primary model. To test our main hypothesis, whether parental context (i.e., Parent Close versus Parent Far) influenced preference for the CS+ in the T-maze, a within-subject repeated measures logistic mixed effects model was performed on the binary outcomes of 1 (CS+ chosen) or 0 (CS- chosen) for each individual trial, which allowed for quantifying both within-subject fixed effects and between-subject random effects. Additionally, we included covariates of toddlers’ sex (female versus male) and age, as well as an AgeXParental Context interaction in the model. In all models, parental context was coded as Parent Close = 0.5 and Parent Far = -0.5, toddlers’ sex was coded as Female = 0.5 and Male = -0.5, and age was mean centered. In glmer syntax:
P(CS+) = intercept + parental context + sex + age + AgeXParental Context + (parental context | participant)
Results (analyzed and visualized in R):
Parental context by age interaction. Age was associated with choosing the CS+ more often in the Parent Close context compared to the Parent Far context in both the Recall Test (T-maze preferences) (β = .08, p = .02) and Recall Test (Computer preferences) (β = .24, p = .006). Plotted are the model fitted regression lines for parental context (Parent Close and Parent Far) with age in months (mean left panel = 31.7; mean right panel = 32.2) on the x-axis and the proportion of CS+ chooses on the y-axis with shaded 95% confidence intervals. The left panel is a repeated measures analysis with 5 trials per parental context and the right panel is a single preference choice per parental context. The dotted line represents chance (50%) for choosing the CS+. Each data point in the left panel represents an individual toddlers’ raw score across all 5 trials per parental context, each data point (jittered) in the right panel represents an individual toddlers’ raw score (1 or 0) for the Parent Absent (grey) and Parent Present (blue) context.
Because results were not as planned, I iterated on the study design in Study 1 and ran Study 2.
Study 2 Methods:
Schematic of Study 2 design: Conditioning and testing paradigm. A. Conditioning phase: During conditioning, toddlers were seated in a highchair next to a familiar teacher. In the Parent Present condition, the parent was also seated next to the toddler. For the Parent Absent condition, the parent was out of the room. B. Recall Test: Following the conditioning phase, while still seated in a highchair, toddlers were presented with two wooden boxes with the CS+ & CS- shapes affixed on top. They were asked to choose from which box they wanted their sticker prize and repeated this protocol 5 times. C. Recall Test (liking): Toddlers viewed the CS+ and CS- shapes on a computer screen, and were asked “Which is your favorite?”.
Results (in R):
Parental context by order interaction. The order of parental context (Parent Present vs. Parent Absent first) significantly interacted with parents' presence to predict toddlers' preference choices (β = -.97, p = .04). Toddlers who underwent the Parent Absent condition first (left panel), were less likely to prefer the CS+ when the parent was absent (choices were significantly different from .5; t(21) = -2.65, p = .01). If toddlers underwent conditioning in the Parent Present condition first (right panel), there was no main effect of parental context on preference choices. The y-axis indicates the probability of choosing the CS+ shape, and the x-axis shows parental context. Mean and standard error bars are model fits and individual subjects’ raw data (percentage of the CS+ chosen across 5 trials) are plotted as individual data points. # indicates p < .05 difference from .5, * indicates p < .05 for the interaction.
Findings and Implications:
Older toddlers (> 3 years old) learn better in the presence of their parent (while they are unengaged, reading a magazine)
Younger toddlers (< 3 years old) avoid rewards when they are left initially in a new room without their parent present (teacher present only)
Younger toddlers (< 3 years old) when oriented to a new room with their parent present, later do change learning when their parent leaves the room
Conclusions: 1. Parents' presence in the room changes learning for toddlers. 2. Parents orienting children to a novel/new space first might help them feel more comfortable and learn better in environments
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