Dev Psych Week 1: Themes & Study Design (Concepts)

The seven course themes

1. How do nature and nurture contribute to development?

2. How richly should we interpret infant behavior?

3. Development does not equate to improvement

4. Developmental science is an active research area

5. Reducing demands on behavior gives new insight into cognition

6. Studying developmental variability enhances understanding

7. How resilient vs. fragile is development?

Theme: Nature and nurture

Definition: nature and nurture work together; the question is how much each shapes a given trait, not which one wins.

Examples: Hershberger chicks, Baldwin effect, epigenetics (Weaver 2004), face-deprived monkeys (Arcaro 2017), live vs. video language exposure (Kuhl 2003)

Theme: How richly to interpret infant behavior

Definition: does longer looking show rich knowledge, or something simpler (novelty, variety, low-level perceptual features)?

Examples: Bulf 2011 vs. Addyman and Mareschal 2013; Cesana-Arlotti 2018; Newman 2010

Theme: Development does not equate to improvement

Definition: some abilities are lost or get worse with age.

Examples: perceptual narrowing (faces and speech); new walkers going over a visual cliff they avoided while crawling; infants matching adults at statistical learning; Simon signing better than his parents

Theme: Developmental science is an active research area

Definition: findings get overturned or shrink when replicated, so what we know keeps changing.

Examples: rule learning (Marcus 1999) failed to replicate; ManyBabies IDS effect smaller than expected; Piaget's object permanence revised; Newman 2010 not yet replicated

Theme: Reducing demands on behavior

Definition: methods that need less behavior (EEG, looking time) reveal abilities that harder, behavior-heavy tasks hide.

Examples: EEG gives better acuity than looking; looking time vs. Piaget's search task; sticky mittens; looking-while-listening

Theme: Studying developmental variability

Definition: differences between infants or between cultures show how development works.

Examples: cultural differences in motor practice; processing speed predicts vocabulary; WEIRD samples

Theme: Resilience vs. fragility

Definition: some abilities develop under almost any conditions (resilient); others need specific input at a specific time (fragile).

Resilient: deaf infants babble with their hands; Simon creates rules from flawed input
Fragile: Genie; critical periods

Design-your-own-study template

1. Question and hypothesis: "If infants can ___, they should ___."

2. Participants: age and why (youngest age the method allows to test innateness)

3. Paradigm: habituation (discrimination), VoE (expectation), preferential looking, HAS (newborns), reaching (5+ mo), EEG/fNIRS (no behavior)

4. Procedure: habituation/familiarization phase, then test; conditions

5. DV: looking time (or sucking rate, reach choice, brain response)

6. Predicted results if hypothesis is true vs. false

7. Controls

Controls in infant studies

Counterbalancing: vary which stimulus is familiar and which side it appears on

Match low-level features: size, color, brightness, motion so infants can't succeed on simple perceptual differences

Control condition: rules out the boring explanation (e.g., within-category change, delayed launching, baseline preference)

Sample size: more than ~20 per group