Sensation and Perception Sensation & Perception 9/18/2018 Sensation and Perception Chapter 4 ©1999 Prentice Hall

Defining Sensation and Perception Sensation & Perception 9/18/2018 Defining Sensation and Perception Sensation The detection of physical energy emitted or reflected by physical objects. It occurs when energy in the external environment or the body stimulates receptors in the sense organs. Perception The process by which the brain organizes and interprets sensory information. ©1999 Prentice Hall

Sensation & Perception 9/18/2018 Ambiguous Figure Colored surface can be either the outside front surface or the inside back surface Cannot simultaneously be both Brain can interpret the ambiguous cues two different ways ©1999 Prentice Hall

Sensation & Perception Processes 9/18/2018 Sensation & Perception Processes Figure 3.Davis 2 from: Kassin, S. (1998). Psychology, second edition. Upper Saddle River, NJ: Prentice Hall. 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. ©1999 Prentice Hall

Sensation & Perception 9/18/2018 Sensory Overload Overstimulation of the senses. Let’s play an observation game! Can use selective attention to reduce sensory overload. Selective attention The focusing of attention on selected aspects of the environment and the blocking out of others. Inattentional blindness Cocktail-party effect Change blindness – people Change blindness – card trick ©1999 Prentice Hall

Sensation & Perception 9/18/2018 Measuring Senses Absolute threshold Difference threshold Signal-detection theory ©1999 Prentice Hall

Sensation & Perception 9/18/2018 Absolute Threshold The smallest quantity of physical energy that can be reliably detected by an observer. ©1999 Prentice Hall

Absolute Sensory Thresholds Sensation & Perception 9/18/2018 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 ©1999 Prentice Hall

Pledge of Allegiance I pledge allegiance

to the flag

of the United States of America

and to the republic

for which it stands

one nation under God

indivisible

with liberty

and justice for all

JND Each slide of the Pledge of Allegiance increased the font size. (28 to 45) Did you notice?

Stimulus Discrimination Sensation & Perception 9/18/2018 Stimulus Discrimination Just Noticeable Difference (JND): The smallest amount of change in a stimulus that can be detected half the time. Weber’s Law JND is proportional to the magnitude of the stimulus The larger the stimulus the larger the change must be to be noticed!! Light, Weight or Tone? ©1999 Prentice Hall

Subliminal Persuasion Derren Brown and Subliminal Advertising

Backmasking!! Secret messages hidden in musical lyrics? Let’s find out!! Jeffmilner.com

Signal-Detection Theory Sensation & Perception 9/18/2018 Signal-Detection Theory A psychophysical theory that divides the detection of a sensory signal into a sensory process and a decision process. (expectations, experience, anticipation) Stimulus is Present Absent Response: “Present” Hit False Alarm Response: “Absent” Miss Correct Rejection ©1999 Prentice Hall

Sensory Adaptation and Deprivation Sensation & Perception 9/18/2018 Sensory Adaptation and Deprivation Adaptation The reduction or disappearance of sensory responsiveness when stimulation is unchanging or repetitious. Prevents us from having to continuously respond to unimportant information. ©1999 Prentice Hall