Children’s Thinking

Lecture 2

Methodological Preliminaries

Children are all different!

Cross-sectional vs. Longitudinal Cross-sectional

Age 1 Age 2 Age 3

LongitudinalAge 1 Age 2 Age 3

Longitudinal Research: Benefits

• Provides individual history – can see developmental & environmental precedents

• Individuals serve as their own controls – minimize individual differences that add noise to comparisons and maximize statistical power

Longitudinal Research: Costs

• Slow – have to wait for subjects to reach appropriate ages

• Subject “mortality” – families lose interest or move out of area, etc.; consequently, the sample at the end of the study is inevitably (much) smaller than the initial sample.

Cross-Sectional Research

• Benefit: by observing different groups of children at different ages, research can be completed more efficiently.

• Assumption: as members of the same species, we share essential cognitive abilities, processes, and representations

• Costs– Individual differences are not just “noise”– Sense of history is lost

Observation vs. Experimentation

• Our goal is to create causal theories that explain how real children develop.

• Unfortunately, the two key components of this goal are in logical conflict.

• To understand causality, we must be able to test behavior under carefully controlled (hence artificial) conditions.

• If we observe in more natural conditions, we forfeit control.

Stimulus Specific Behaviors

Infants are born with a large repertoire of reflexive behaviors. Some of these have obvious survival value, ensuring approach to nurturing stimuli or avoidance of noxious stimuli. Other reflexes have no apparent function. The presence of these reflexes is evidence of a healthy brainstem. As the cortex develops, many of these reflexes come under voluntary control; others disappear entirely by 4 months. Reappearance of these reflexes is a sign of cortical damage. Some of the newborn reflexes are described on the following slides.

Newborn Reflexes

• Rooting: When baby's cheek is stroked at the corner of her mouth, her head will turn toward finger and she will make sucking motions.

• Sucking: A finger or nipple placed in baby's mouth will elicit rhythmical sucking.

• Babinsky: Baby's foot is stroked from heel toward the toes. The big toe should lift up, while the others fan out.

Newborn Reflexes

• Stepping: Holding baby upright with feet touching a solid surface and moving him forward should elicit stepping movements.

• Palmar grasp: Pressing one of the baby’s palms causes fingers to grasp.

• Babkin: When both of baby's palms are pressed, her eyes will close, mouth will open and her head will turn to one side.

Stimulus Specific Behaviors: Optokinetic Nystagmus

Visual Gratings

Listening preference

• Normally, infants cannot control auditory stimulation, but in circumstances in which auditory stimuli are made contingent on some aspect of the infant’s behavior, infants reveal listening preferences.

• In contrast to visual preferences, early auditory preferences tend to be for familiar, relatively simple stimuli. This may be because testing for auditory preference is inherently more complex, requiring infants to learn some novel contingency.

Headturn preference procedure

Infants’ listening preference: Baby talk or happy talk?

Singh, Morgan, & Best, 2002Six sets of stimuli:

• Infant-directed speech

happy - sad - neutral

• Adult-directed speech

happy - sad - neutralHappy Neutral Sad

Infant-directed

Adult-directed

Do Infants Still Prefer Baby Talk when Affect is Held

Constant?

• Subjects: 36 infants at 6 months

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Sad

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Happy Neutral SadAffect

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Do Infants Prefer Happy Talk or Baby Talk?

• Subjects: 32 infants at 6 months

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Happy vs. Neutral Neutral vs. HappyExperimental Group

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Can Infants Use Their Own Names to Learn New Words?

(Bortfeld, et al., 2005)

Using the Headturn Preference Procedure, infants Maggie and Hannah were familiarized with two passages:

Maggie’s bike had big, black wheels Hannah’s cup was bright and shiny

The girl rode Maggie’s bike A clown drank from Hannah’s cup

The bell on Maggie’s bike was really loud The other one picked up Hannah’s cup

She knew Maggie’s bike could go very fast Hannah’s cup was filled with milk

The boy played with Maggie’s bike She put Hannah’s cup back on the table

Maggie’s bike always stays in the garage Some milk from Hannah’s cup spilled on the rug

Can Infants Use Their Own Names to Learn New Words?

After familiarization, infants were tested on their preference for four words:

bike cup feet dog

A Fish Story[Louis] Agassiz would ask the student when he would like to begin. If the answer was now, the student was immediately presented with a dead fish -- usually a very long dead, pickled, evil-smelling specimen -- personally selected by "the master" from one of the wide-mouthed jars that lined his shelves. The fish was placed before the student in a tin pan. He was to look at the fish, the student was told, whereupon Agassiz would leave, not to return until later in the day, if at all.

Samuel Scudder, one of the many from the school who would go on to do important work of their own (his in entomology), described the experience as one of life's turning points.

In ten minutes I had seen all that could be seen in that fish.... Half an hour passed -- an hour -- another hour; the fish began to look loathsome. I turned it over and around; looked it in the face -- ghastly; from behind, beneath, above, sideways, at three-quarters view -- just as ghastly. I was in despair. I might not use a magnifying glass; instruments of all kinds were interdicted. My two hands, my two eyes, and the fish: it seemed a most limited field. I pushed my finger down its throat to feel how sharp the teeth were. I began to count the scales in different rows, until I was convinced that that was nonsense. At last a happy thought struck me -- I would draw the fish, and now with surprise I began to discover new features in the creature.

When Agassiz returned later and listened to Scudder recount what he had observed, his only comment was that the young man must look again.

I was piqued; I was mortified. Still more of that wretched fish! But now I set myself to my task with a will, and discovered one new thing after another.... The afternoon passed quickly; and when, toward its close, the professor inquired: "Do you see it yet?"

"No," I replied, "I am certain I do not, but I see how little I saw before."

The day following, having thought of the fish through most of the night, Scudder had a brainstorm. The fish, he announced to Agassiz, had symmetrical sides with paired organs. "Of course, of course!" Agassiz said, obviously pleased. Scudder asked what he might do next, and Agassiz replied, "Oh, look at your fish!"

What is Development?

• Change of a certain sort– Orderly– Directional– Cumulative

• Behavior becomes more flexible and complex

• Behavior involves increasing differentiation and integration

What is Cognition?

• We usually use “thinking” to refer to higher order mental processes like judgment, problem solving, conceptualizing, etc.

• Here, we are concerned not only with these, but also with basic aspects of everyday mental processing.

• These include:– remembering– recognizing objects as exemplars of particular

categories of objects – representing the external world