Chapter 8: Sensation & Perception Psychology Mr. Schabo Crestwood High School

Do-Now: (Discussion) If you had to sacrifice one of your five senses: Sight Hearing Touch Smell Taste Which one would it be? Why?

Sensation vs. Perception What occurs when a stimulus (change in environment, to which an organism responds) activates a receptor Perception: The organization of sensory information into meaningful experiences

Ambiguous Figure Colored surface can be either the outside front surface or the inside back surface of the cube Cannot simultaneously be both Brain can interpret the ambiguous cues two different ways

The Riddle of Separate Sensations Sense receptors Specialized cells that convert physical energy in the environment or the body to electrical energy that can be transmitted as nerve impulses to the brain.

Sensation & Perception Processes

Doctrine of Specific Nerve Energies Different sensory modalities exist because signals received by the sense organs stimulate different nerve pathways leading to different areas of the brain. Synthesia A condition in which stimulation of one sense also evokes another.

“Fraser’s Spiral”

Why does this image appear to be a spiral? “Fraser’s Spiral” Why does this image appear to be a spiral?

“Fraser’s Spiral” In viewing “Fraser’s Spiral:” What are we sensing? What are we perceiving? How do we use sensation and perception together to understand our world?

Measuring Senses Absolute threshold Difference threshold Signal-detection theory

Absolute Threshold The smallest quantity of physical energy that can be reliably detected by an observer.

Absolute Sensory Thresholds Vision: A single candle flame from 30 miles on a dark, clear night Hearing: The tick of a watch from 20 feet in total quiet Smell: 1 drop of perfume in a 6-room apartment Touch: The wing of a bee on your cheek, dropped from 1 cm Taste: 1 tsp. Sugar in 2 gal. water

Difference Threshold The smallest difference in stimulation that can be reliably detected by an observer when two stimuli are compared; Also called Just Noticeable Difference (JND).

Spot the differences…How many can you find?

Difference Threshold

Sensory Adaptation Sensory Adaptation: Senses tuned to change; adaptable Responsive to increases and decreases of stimuli E.g.: Eyes adjust to darkness in a movie theatre Skin adapts to coldness of ocean water

What would happen if we did not have “sensory adaptation?” Can you think of other examples of how our senses adapt to changes in external stimuli? What would happen if we did not have “sensory adaptation?”

Without Sensory Adaptation.. Without sensory adaptation, the human body would be overloaded with stimuli. For example, right now we would be feeling the constant pressure of the clothing we are wearing, the chairs on which we are seated, etc.

“The Disappearing Circle”

“The Disappearing Circle” When focusing on the black dot, why does the outer grey circle appear to fade away?

Signal-Detection Theory Signal Detection Theory describes the relations between motivation, sensitivity, and decision making in detecting the presence or absence of a stimulus. With everything going on around us, how and why so we choose to focus on the things we do?

“The Stroop Effect” (Part A.)

“The Stroop Effect” (Part B.)

“The Stroop Effect” (Part C.)

“The Stroop Effect” Why is it more difficult to name the colors in “Part C.?” The “Stroop Effect” illustrates how difficult it is to ignore some kinds of stimuli You were receiving two stimuli – the color and the word – which compete and slow you down when you try to name the color

Review What is the difference between sensation and perception? What is sensory adaptation? Why do humans adapt to stimuli?