Biological Basis of Cognitive

DevelopmentLecture: Unit 2

Dr. Neil SchwartzPsych 353

Natural Selection

Variability

Survival

Reproduction

Phenotype

Genotype

Biston betularia f. typica, the white-bodied

Biston betularia f. carbonaria, the black-bodied peppered moth.

DNA Transcription

Genetic activity (DNA RNA proteins) structural maturation function, activity

The emergence of new structures and functions during the course of development.

Development is characterized by an increase of complexity of organization.

Reflects a biderectional relationship between all levels of biological and experiential variables, such that genetic activity both influences and is influenced by structural maturation, which is bidirectionally related to function and activity.

Epigenesis

Developmental Systems Approach suggests that development occurs as a function of the interaction between multiple layers of an organism and its environment.

Epigenesis suggests that a human, at any given developmental level, will be qualitatively different—both in terms of structure (what they look like/what they know) and function (what they can do). These changes occur at all levels of an organism because of bi-directional relationships with all of these levels.

Developmental Systems and the Concept of Epigenesis

There are constrains ( genetics and environment)

EX. Breast milk and IQ

Right and left hemispheres are not symmetrical

All four levels influence each other bi-directionally...

Environment Behavior Neural Activity Genetic Activity

Consider the levels and what they can do...

There are no simple genetic or experiential causes of behavior. Instead, the two interact to increase or decrease the probability of behavior based on the interaction of genetic predisposition and experience.

But, remember… experience is not just experience generically defined. Rather it is species-typical environmental experience—both prenatally and postnatally.

The Answer?

Critical periods are the time in development when infants/children are “ripe” for the influence of environmental experiences. (when a specific skill or ability is most easily acquired)

Humans are prepared neurologically for certain experiences and not others. When the time is right, the experiences exert their most effective and efficient effect on development.

Critical Periods

Ex. Bobwhite Quails

Neurological preparedness suggests that there are undifferentiated neurons that become specialized for various functions as a result of their location in the brain and experience. When these neurons are made available for differentiation, the nature of experience can and will have a clear effect on them, and hence on all of development.

What does it mean to be neurologically-prepared?

Genes direct biochemical production (proteins, for example).

Bio-chemicals determine structural development (like various tissues—nerves, muscles, bones).

Use or disuse of these structures (nerve cells or muscle cells, for example) can turn genes on or off —which in turn can create or allow to atrophy nerve or muscle cells.

So, what is the support for the bi-directional effects of biology and experience?

Behavior Genetics — studies genetic effects on behavior and complex psychological characteristics, such as intelligence and personality.

So, is biology truly destiny? No… remember, all genetic effects are

moderated by environmental effects.

Behavior Genetics

A person’s genetic makeup influences which environments one encounters and the type of experiences one has.

Genes drive experience and determine how we organize our world and how our experiences are perceived.

Genotype Environment Theory

Child’s Genotype

Environment sought out and established by

the Child

Child’s Phenotype

Rearing Environment of

the Child

Phenotype of the Child

Genotype of the Child

Genotype of the Parents

Passive Genotype — The environmental influences that parents provide for their kids exert a gradually decreasing effect on the children as the children get older.

Environmental effects decrease with age.

Genetic and Environmental Influences on Human Development

Evocative Genotype — Temperamental characteristics of children that elicit responses from others.

Environmental effects remain constant with age.

Genetic and Environmental Influences on Human Development

Active Genotype — As children get older, they have more and more ability to select environments that suit their own particular needs.

Environmental effects increase with age.

Genetic and Environmental Influences on Human Development

Biologically primary abilities: Abilities which are selected in evolution, acquired universally, and that draw high motivation from children to perform tasks involving them. Ex: language

Biologically secondary abilities: Culturally invented skills built atop primary abilities. Repetition and external pressure are used to learn such skills. Ex: reading

Possible reasons for extended period of immaturity: ◦ Children need a good deal of time and practice to “master

the complexities of human societies and technologies;”◦ Humans live with a variety of social and physical

environments, and as such, they need much cognitive flexibility to adapt to such differences;

◦ We need “a long period of apprenticeship, as well as a large brain capable of flexible learning and cognition.”

Biological functions of the brain are important to touch on, because talking about cognition and cognitive functions is relatively unexciting without knowledge of the way the brain works. So much more is known about the brain today that validates theories of cognition.

Introduction

Myelinated Neuron

Unmyelinated Neuron

fMRI ScanPET Scan

Therefore, characteristics of the child, as well as the rearing environment and genetic

contributions of the parents, influence the course of development.

Domain-specific modules David Geary’s model of domain-specific

modules:◦ Social

Individual Group

◦ Ecological Biological Physical

Central idea: Cognitive and behavioral variability within an individual are subject to environmental selection. Adaptive cognitions or behaviors increase in frequency and non-adaptive ones decrease or cease.

Seemingly a process of trying out strategies in order to find those that are most effective.

Brain development: Neurons produced in great variability and numbers; adaptive ones survive and others do not.

Selectionist Theories of Cognitive and Brain Development