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Biological Psychology:Mechanisms

James Kalat

N. C. State University

1. Taste Receptors:sweet, sour, salty, bitter, umami

• Tea made from leaves of gymnema sylvestre block sweet tastes. (Also block intestinal absorption of carbohydrates.)

2. Neurons and the Action Potential

• No loss of intensity as action potential travels

• Can be relatively slow.

• Demonstration of action potential speed

Velocity of Action Potential =

Mean distance from ankle to shoulder/mean difference in response latency =

About 1.5 meters/ ______ =

Correct reference:

• Rozin, P., & Jonides, J. (1977). Teaching of Psychology, 4, 91-94.

Vision

How far can an ant see?

3. Color Vision

Young-Helmholtz theory (=trichromatic theory)

Color Vision

Opponent-process theory

Rods and cones:• Cones in fovea (center); rods

more common toward periphery

• Cones for color; rods for b/w

• Therefore: Colorblind in periphery. Demonstration

Opponent process theory of color vision:

We perceive by three pairs of opposites:

• Red versus green

• Yellow versus blue

• White versus black

• Evidence: Negative afterimages

Retinex theory of color vision

• We perceive color and brightness by contrasting each image with the rest of the scene.

• Combine retina and cortex.

• Produces color constancy: Same color despite changes in lighting.

4. Motion Blindness

What would it be like to have that experience?

Is the continuous stream of consciousness really continuous?

Temporary blindness implies temporary gaps in consciousness

5. Developmental Changes

Visual-motor control

Max, age 4 Ann, age 7

Changes in Decision-making:

Adolescents slower than adults to classify

something as “bad idea.”

Changes in Decision-Making

Adolescents slower than adults to classify something as a “bad

idea.”

Changes in Anxiety:

Allopregnanolone = steroid released by stress.

Allopregnanolone decreases anxiety through one kind of GABA receptor, increases it through another kind. The second kind is rare in children and adults, but abundant in adolescents.

6. Facilitation of the Startle Reflex

Location of the

Amygdala