Chapter 1Learning to Change

Learning Learning is a change in the behavior of

an organism due to experience.

Behavior is anything that an organism does that can be measured.

Experience: exposure to events that affect (or are capable of affecting) behavior. We call these events stimuli. Stimuli are physical events that can originate

outside the body or inside the body.

Change: Environmental and Behavioral Organisms live in specific environments and

must adapt to those environments to thrive.

Problem: Environments change. Slow Changes (beyond the life of individual

organisms): Continental drift, ice ages, global warming,

desertification, deforestation, depopulation Changes during a lifetime

Natural disasters, weather, predators, illness

Solutions: Organisms must change.

Change

Species Change: Evolution by Natural Selection Gradual change in the distribution of

physical and behavioral characteristics in populations of organisms.

Individual Change: Learning

Darwin’s Theory of Natural Selection Darwin contrasted natural

with artificial selection. Animal breeders select

physical and psychological characteristics through controlled breeding of animals.

But suppose: Unfriendly and aggressive fox’s (for whatever reason) were sterile or died before reproducing.

Only docile and friendly fox’s would reproduce. Those traits would grow in frequency in the fox population.

The consequence would be the same as if the foxes were mated by artificial selection.

Belyaev and Trut (1999)

Natural Selection

Natural selection is an evolutionary process through which adaptive traits are passed on to ongoing generations because these traits help

animals survive and reproduce.

In natural selection, nature (the environment) determines what traits get transmitted.

If a trait leads to death before reproduction or interferes with reproduction (maladaptive traits), it gets weeded out of populations over time.

If a trait increases survival and reproduction (adaptive fitness), the trait is transmitted to offspring.

By this process, traits increase or decrease in frequency in populations.

Natural Selection

Natural selection is NOT a theory of The origins of nature, or being-as-such The origins of life It is a theory of changes in

characteristics of a species, and potentially of the origins of new species (arising from existing species).

Blind Variation and Selective Retention. Natural selection is an example of a

broader class of processes that lead adaptive change.

Donald Campbell: BVSR processes

In such a process there are three essentials: (a) Mechanisms for introducing variation; (b) Consistent selection processes; and (c) Mechanisms for retaining and/or

propagating the selected variations.

Try Things, Keep What Works Try Things (Variation), Keep (Retention) What Works (Selection)

Examples of BVSR processes

Process Variation Selected by Retention

Language Learning

Infant Babbling Parents/Community

Brain/Memory

Creative Arts Production of ideas

Artistic Judgment

Brain/Memory/Archives

Immune System Random Antibodies

Antigens (Invaders)

Cloning

Evolution Recombination/Mutations

Nature/Environment

Genetic Code of Offspring

What Darwin didn’t know…

Genes: produce proteins Proteins: Produce physical structure of

organisms Including brains and nervous systems—hence the relevance

to psychology.

Sexual Reproduction: Produces variation in genes (and hence in physical structures and psychologies) through recombination. Variation in genes can also occur through mutations If mutations occur in reproductive cells, these can

also be passed on to offspring.

Peppered Moths

Frequencies of moth colors “selected” by industrial soot.

Easily seen mothspicked off by predators

Classes of Behavior

FROM: TO:

Species-Specific Mechanisms

Cross-Species Mechanisms

Highly Heritable Low Heritability

Stereotypical Patterns, Relatively Unmodifiable

Flexible Patterns,Relatively Modifiable

Simple Responses Potentially Complex Behaviors

Reflexes Modal Action Patterns

General Behavior Traits

Learned Behaviors

Reflexes A reflex is a relationship between a

specific event and a simple response to that event.

Often protect organisms from injury. Example: Withdrawal Reflex

Also:*eyeblinks*sneezing*vomiting

Human Infant Reflexes

Rooting (touch cheek turn) Sucking (when nipple placed in mouth) Food Salivation Food & Saliva Swallowing Swallowing peristalsis (motion in

esophagus that carries food to stomach)

All very useful, promotes survival, and does not require learning.

If only. . . Calculus reflex

Phenomena Assoc/w Reflexes

Sensitization: Eliciting a reflex often leads to an increase in the probability or intensity of a response to the same (or closely related) stimuli.

Loud noises can elicit the startle response (jump).

We are more likely to startle again immediately afterword (no other, even weaker) noises.

Scary movies?

Phenomena Assoc/w Reflexes

Habituation: Repeatedly evoking a reflexive response will often weaken or decrease the probability of a response to the same stimulus.

Sokolov: the orienting response (OR) in dogs New Stimulus looking toward stim., ears lift,

wave of neural and physiological activity (HR, breathing, etc)

With time, OR fades; appears that organism no longer aware of stimulus.

Habituation

Modal Action Patterns A series of interrelated actions found in most

members of a species, usually triggered by specific stimuli (called “releasers,” or “releasing stimuli”) Usually involves the whole organism (unlike

reflexes, which often involve specific muscles or glands).

Are more complex than reflexes, extended over a longer period of time.

They are stereotypical, but more variable than reflexes.

They often appear to be a long chain of reflexes following one another.

(Used to be called “fixed action patterns.”)

Example MAPs

Examples: Spider web

spinning Cat defensive

posture (hiss, arch back, fur on end, tail swishing—makes cat seem larger, more threatening)

Playing possum Courtship &

mating dances

General Behavior Traits Broad behavioral tendencies that occur

across many situations (no inborn, specific releasers).

Often highly heritable (EAS; R. Plomin): Activity Levels Sociability (tendency to approach and interact

with others—highly variable in young children) Emotionality (e.g., fearfulness)

Basically, temperament and personality by another name.

Learning Reflexes, MAPS, and General Traits are

often adaptive. They have likely evolved over centuries

and perhaps help organisms coping with their average expectable environments.

But there are still day-to-day surprises, changes within an individual’s lifetime.

The capacity for flexible change in a lifetime is probably an evolved capacity as well.

Learning is Evolved Modifiability.