Unit IV: Sensation & Perception Mrs. O’Connor AP Psychology

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

“Fraser’s Spiral”

 Why does this image appear to be a spiral?

Sensation vs. Perception  Sensation:  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

“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?

“The Disappearing Circle”

 When focusing on the black dot, why does the outer grey circle appear to fade away?

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

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 Stroop Effect” (Part A.)

“The Stroop Effect” (Part B.)

“The Stroop Effect”  Why is it more difficult to name the colors in “Part B.?”  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?

The Human Eye

 Lens The lens sits directly behind the pupil. This is a clear layer that focuses the light the pupil takes in. It is held in place by the ciliary muscles, which allow the lens to change shape depending on the amount of light that hits it so it can be properly focused.

 CorneaThe cornea is the outer covering of the eye. This dome-shaped layer protects your eye from elements that could cause damage to the inner parts of the eye. The cornea also allows the eye to properly focus on light more effectively.

 RetinaThis is made of rods and cones arranged in layers, which will transmit light into chemicals and electrical pulses. The retina is located in the back of the eye, and is connected to the optic nerves that will transmit the images the eye sees to the brain so they can be interpreted

 PupilThe pupil appears as a black dot in the middle of the eye. This black area is actually a hole that takes in light so the eye can focus on the objects in front of it.

 Iris The iris is the area of the eye that contains the pigment which gives the eye its color. This area surrounds the pupil, and uses the dilator pupillae muscles to widen or close the pupil. This allows the eye to take in more or less light depending on how bright it is around you. If it is too bright, the iris will shrink the pupil so that they eye can focus more effectively.

 ScleraThe sclera is commonly referred to as the "whites" of the eye. This is a smooth, white layer on the outside, but the inside is brown and contains grooves that help the tendons of the eye attach properly. The sclera provides structure and safety for the inner workings of the eye, but is also flexible so that the eye can move to seek out objects as necessary.

Optic Nerve- The nerve that carries neural impulses from the eye to the brain.

 Ciliary Body (muscle)- The ciliary body also contains the ciliary muscle, which changes the shape of the lens when your eyes focus on something. This process is called accommodation.