1. Out of Sight, But Not Out of Mind (1954) Lydia Welty Abraham Park

2. Background ●Jean Piaget - Swiss Psychologist ●Object Permanence: understanding that objects continue to exist even when they cannot be observed ●Sensorimotor stage (0~2): full object perseverance development ●Hypothesis: older children do not only learn more, but think differently than younger children

3. Experimental Method Procedures: Unstructured Evaluation Methods (observation) ●Games with own children ●Observed errors and problem-solving ability Losing interest in hidden object = lack of OP Searching for hidden object = evidence of OP OP - Object Permanence

4. Findings: Six Stages 1.Touch/Feeling Reflexes 2.Primary Circular Reactions + Passive Expectation 3.Secondary Circular Reactions 4.Objects Don’t Disappear + A-not-B Effect 5.Visible Displacements 6.Invisible Displacements + Object Permanence

5. Historical Significance ●Basis of Piaget’s work of four stages of cognitive development ●Claims that all stages are applied universally to all children - ages approximate - all stages invariable - changes gradual - behaviors do not disappear completely

6. Controversies Controversies: -some neglect that cognitive development happens in discrete stages - intellectual development is continuous - cognitive abilities are results of modeling and one’s learning and conditioning history -Use of his own children

7. Subsequent Research -Renee Baillargeon: Infants as young as 2 ½ months show signs of possessing object permanence. -Wilcox/Nadel/Rosser: Tested premature infants (using Baillargeon’s methods) to show signs of object permanence. -Scher/Amir/Tirosh: Infants with an advanced understanding of object permanence had fewer sleep difficulties