1. CHAPTER 4 – SENSATION AND PERCEPTION SECTION 1 – SENSATION AND PERCEPTION: THE BASICS Objective: DISTINGUISH BETWEEN SENSATION AND PERCEPTION, AND EXPLAIN HOW THEY CONTRIBUTE TO AN UNDERSTANDING OF OUR ENVIRONMENT.

2. KEY TERMS sensation – the stimulation of sensory receptors and the transmission of sensory information to the brain. perception – the process of organizing and interpreting sensory information. absolute threshold – the smallest amount of a particular stimulus that can be detected. difference threshold – the minimum difference that an individual can detect between two stimuli. signal-detection theory – the idea that distinguishing sensory stimuli takes into account a person’s physical state, mood, and attitude as well as the strength of the stimuli.

3. I. Sensation and Perception A. Absolute Threshold 1. The weakest amount of a stimulus that can be sensed. 2. Absolute threshold is different from person to person. a. Can stem from psychological or biological factors. B. Difference Threshold 1. The minimum amount of difference that can be detected between two stimuli. 2. Ex. shades of color, similar tones

4. C. Signal-Detection Theory 1. A method of distinguishing sensory stimuli that considers strength, setting, physical state, mood, and attitude. 2. Psychological factors such as motivation, expectation, and learning. 3. We focus on whatever we consider important. D. Sensory Adaptation 1. Process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli.

5. SECTION 2 – PERCEPTION OBJECTIVE: SUMMARIZE THE LAWS OF SENSORY PERCEPTION.

6. KEY TERMS: closure – the tendency to perceive a complete or whole figure even when there are gaps in sensory information. proximity – the perceptual tendency to group together visual and auditory events that are near each other. similarity – the perceptual tendency to group together elements that seem alike. continuity – the perceptual tendency to group stimuli into continuous patterns. common fate – the tendency to perceive objects that are moving together as belonging together.

7. KEY TERMS CONTINUED: stroboscopic motion – visual illusion in which the perception of motion is generated by the presentation of a series of stationary images in rapid succession. monocular cue – a cue for distance that may be available to either eye alone. binocular cue – a visual cue for depth that requires the use of both eyes. retinal disparity – a binocular cue based on the difference between the two images of an object that the retina receives as the object moves closer or farther away.

8. II. Perception A. Rules of Perceptual Organization 1. closure – tendency to perceive a complete or whole figure even when there are gaps in what your senses tell you. 2. Figure-Ground Perception – the perception of figures against a background. 3. Proximity – perception of figures based on nearness. 4. Similarity – grouping figures together based on likeness.

9. 5. continuity – perception based on a preference for smooth, continuous patterns. 6. common fate – perceiving things as belonging together because they appear to have the same purpose. B. Perception of Movement 1. To sense movement, one must be able to see an object change position relative to other objects. C. Stroboscopic Motion 1. The illusion of motion based on the rapid progression of images/objects that are not moving at all.

10. D. Depth Perception * The perception of distance. 1. Monocular Cues a. Need only one eye to be perceived. b. Used by artists to create the illusion of depth. * perspective * clearness * overlapping * shadow * texture gradient

11. 2. Binocular Cues a. both eyes are required b. retinal disparity – the difference between two images seen by each eye. c. convergence – the closer an image gets to our eyes, the more inward our eyes turn or converge. E. Perceptual Constancies 1. Size constancy – tendency to perceive an object as being on size no matter how far away it is. 2. color constancy – tendency to perceive objects as keeping their color even though lighting might make color appear different.

12. 3. brightness constancy – tendency to perceive an object as equally bright regardless of lighting.