Sensation and Perception

Sensation and Perception

• Sensation: stimulation of sense organs

• Perception: selection, organization, and interpretation of sensory input

Five senses:Vision

HearingTouchTasteSmell

We do not view the world as it is, but instead actively construct a perception of it,

Vision - components

Cornea: where light enters the eye Lens: focuses the light rays on the retinaIris: colored ring of muscle, constricts or dilates via amount of lightPupil: regulates amount of lightCones: adapted for color vision, daytime light, and detailed visionRods: adapted for vision in dim light

Vision - color

Figure 4.12

A replica of the Ishihara test for color blindness.

Vision - color

Figure 4.9

Negative afterimages. Stare at the dot near the middle of the flag for at least 30 seconds. Then look immediately at a plain sheet of white paper or a white wall. You will see the American flag in red, white, and blue. Reduced sensitivity to green, black, and yellow in the visual system, caused by prolonged staring, produces the complementary colors.

Vision - color

Brightness Constancy. The orange squares within the blue squares are the same hue, yet the orange within the dark blue square is perceived as brighter. Why?

Vision - color

Vision - Acuity

Vision – Gestalt principles

Vision – Reversible Figures

Vision – Perceptual Set

Vision – Subjective Contours

Vision – Subjective Contours

Vision – Distal and Proximal Stimuli

Vision – Perceptual illusions

Vision – Perceptual illusions

The trade-off between size and distance: A given image on the retina can indicate either a small, close object or a large, distant object.

Vision – Size and Distance

One of the drawings used by Mackworth and Loftus (1978) to investigate attention. Observers attend to unexpected objects longer than they do to expected objects. In this drawing, observers looked longer at the octopus than they did at a tractor placed in the same spot. What do you think would happen if a tractor were shown upside down or on the roof of the barn?

Vision – Attention

Vision – Depth

Vision - Depth

Vision - Movement

More examples on the internet…

• Left-handed v. Right-handed quiz http://www.illusions.1570films.com/

• Illusions - many exampleshttp://www.scientificpsychic.com/graphics/

• I still can’t figure this out! http://www.tommcmahon.net/2003/12/12_then_13_guys.html

(2) Hearing - components

Hearing – source and loudness

(3) Touch - Components

Figure 4.49 The tongue and taste

(4) Taste - Components

(5) Smell - Components