Psych_Outline_Chapter 5

Psych_Outline_Chapte - Psychology Chapter 5 Sensation Sensation detect physical energy from environment and encode it as neural signals Perception

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Psychology Chapter 5: Sensation Sensation- detect physical energy from environment and encode it as neural signals Perception- select, organize, interpret sensations Bottom-Up Processing- analysis that begins with sensory receptors and works up to brain’s integration of sensory information Top-Down Processing- info processing guided by higher level mental processes, as when we construct perceptions drawing on our experience and expectations. Sensing the World: Some Basic Principles I. Thresholds Psychophysics- study of how physical energy relates to our psychological experiences a. Absolute thresholds- minimum stimulation necessary to detect particular light, sound, pressure, taste or odor 50% of the time i. 50-50 recognition point defines your absolute threshold. b. Signal Detection- theory predicting how and when we detect presence of faint stimulus amid background stimulation (noise). i. Detecting weak stimulus (signal) depends not only on signal strength but on psychological state (experience, expectations, motivation, alertness) 1. No single absolute threshold 2. Different response to same stimuli under different conditions c. Subliminal Stimulation i. Can unconsciously sense subliminal (below threshold) stimuli ii. Priming- activation (often unconsciously) of certain associations, thus predisposing one’s perception, memory or response 1. sometimes we feel what we do not know and can’t describe iii. subliminal procedures offer little or nothing of value to marketers. d. Difference Threshold- (just noticeable difference/jnd) minimum difference a person can detect b/w any 2 stimuli half the time. i. Increases with the magnitude of the stimulus. ii. Regardless of magnitude, 2 stimuli must differ by constant proportion for their difference to be perceptible 1. Weber’s Law- diff threshold is not a constant amount but some constant proportion of the stimulus. a. Exact proportion varies depending on the stimulus b. Thresholds for detecting differences are roughly constant proportion of the size of the original stimulus.
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II. Sensory Adaptation a. Diminished sensitivity as a consequence of constant stimulation. i. After constant exposure to unchanging stimulus, nerve cells fire less often b. Perceptions are organized by the meanings that our minds impose c. Reduced sensitivity enables us to focus on informative changes in environment w/o distraction from uninformative/constant stimulation. i. Sensory receptors are alert to novelty ii. Repetition bores them and then they’re free for more important things d. We perceive the world not exactly how it is but as its useful for us to perceive it. Vision
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This note was uploaded on 04/19/2008 for the course PSY 1001 taught by Professor Waddell during the Fall '08 term at Villanova.

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Psych_Outline_Chapte - Psychology Chapter 5 Sensation Sensation detect physical energy from environment and encode it as neural signals Perception

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