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4th Edition

Sensation and Perception

Chapter 3

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Sensation, Perception and Psychophysics

• Vision

• Hearing

• Taste

• Smell

• Body position

• Movement

We receive and process information about:

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Sensation, Perception and Psychophysics

What is sensation? Perception?

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Sensation, Perception and Psychophysics

• Receptors > respond to only one type of stimulus.

• Transduction

• Adaptation > presentation of same stimulus results in loss of sensitivity.

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Subliminal Perception

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Sensory SystemsVision

• Light waves differ in terms of wavelength (hue) or color, amplitude (intensity), and saturation (purity).

• The psychological counterpart of wavelength is color.

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Additive and Subtractive Processes of Color Mixing

• Radiant light is visible energy emitted by an object• Reflected light

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Sensory SystemsVision

• Sensory systems of eye: Rods and Cones. –Cones have greater acuity

• respond to color• higher threshold for activation• ~ 7 million per eye.

– Rods have lower acuity• respond to black and white [and shades of gray] • more sensitive• ~120 million per eye.

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Sensory Systems

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Sensory SystemsVision

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Two theories of color vision

• Trichromatic theory: three types of cones• Opponent-process theory: color-sensitive cells

arranged in pairs.– Pairs of Yellow-Blue and Red-Green Cones

• Both theories are supported by research findings.

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Color Blindness

• Dichromats lack the ability to see one of the three primary colors.

• Monochromats are unable to see color.

IshiharaPlates

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Ishihara Plates

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Sensory SystemsAudition

• Audition > movement of molecules in the air.

• Varies by wavelength (frequency), amplitude (intensity), and purity (timbre)

1) Vibration of the eardrum;

2) Movement of fluid in the inner ear;

3) Bending of specialized hair cells (receptors for hearing).

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Sensory Systems

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Organ of Corti

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Tectorial MembraneBasilar Membrane

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Sensory SystemsGustation

• Molecules in solution stimulate taste.

• Each receptor may respond to several tastes, but each one is maximally sensitive to one of four tastes salty, sweet, sour, or bitter

[metallic, alkaline savory, meaty?]

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Olfactionp.108

• Molecules in the air stimulate the sense of smell.

• Receptors attach to olfactory bulb.

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Smell and Emotions

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Sensory Systems Vestibular Sense

• Enables us to adjust to different bodily movements.

• Orientation, gravity

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Sensory Systems Kinesthetic Sense

• Location and position of body parts.

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Sensory SystemsCutaneous Senses

• Mechanoreceptors• Nocioreceptors• Thermoreceptors

Cutaneous receptors located in the skin:

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PerceptionSize Constancy

• We experience perceptual constancies when our perception of an object does not change, even though the retinal image does change.

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Shape Constancy

Perception of shape remains constant even though image on retina changes.

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Depth Perception and Binocular Disparity

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Depth Perception and Binocular Disparity

Close objects translate very fast (brush) and distant objects pass very slow (mountains).

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Binocular Disparity

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Monocular Cues

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Gestalt Principles of Perception

• We actively organize our perceptual world into meaningful groups or wholes.– Proximity– Similarity– Continuity – Closure

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Perception

• Perceptual hypotheses are inferences about the nature of the stimuli we sense.

• Perceptual illusions and ambiguous figures may cause us to develop incorrect perceptual hypotheses.

• Hermann grid

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Ames Room

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The size of a familiar object is perceived as largely distorted, because the misleading geometry generates an incorrect frame of reference

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Zener Cards

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Skeptics