Psych3 - Sensation and Perception October 9 2007 I The...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Sensation and Perception October 9, 2007 I. The difference A. Sensation: reception of stimulation from the environment, immediate experience in response to stimulation coming in, hitting the sensory neurons, and getting that info to the brain 1. Stimulus: any form of energy that activates a sense receptor- Ex: eyes: light rays; nose and mouth: chemicals; touch: pressure or heat B. Perception: very much related to sensation, but what happens in the brain after sensation occurs, psychological process by which we give meaning to the sensation 1. Interpretation of shapes: 2. Involves memory of past sensation memory experience 3. New things involve a lot more time to interpret II. Psychophysics A. Absolute threshold: smallest intensity of a stimulus that can be detected- how much sound does there have to be before you can hear it? 1. Traditionally tested by presenting people with varying stimuli and asking people whether or not they heard it a. Problems: Difficult to measure because people vary in sensitivity to stimuli, Sensitivity to stimuli vary at different times: when somebody is tired, 2. Noise” the more noise there is in an environment, the harder it will be to detect the stimulus 3. Threshold is defined as the magnitude of the stimulus when a person can detect it 50% of the time 4. Signal Detection Theory: present a stimulus on some of the trials, don’t present to some, can chart a persons responses w/ actual stimulant presence a. Sound a tone and response is: heard it HIT b. Sound a tone and isn’t hear: MISS c. Do not sound a tone and heard it: False alarm d. Do not sound a tone and did not hear it: Correct Rejection 5. Can compute: d= hits/false alarms- the greater the ratio, the more sensitive a person is to the stimulus 6. Examples: Each subject tested 50 times a. Joe: 25/25; d’= 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
b. Jake: 25/5; d’= 5 c. John: 5/25; d’= 0.2 d. Jerry: 5/5; d’= 1 7. Response bias: may be either conservative or liberal a. Conservative: claim to have detected the signal only when you are absolutely certain that you have; raise the ratio b. Liberal: claim to have detected the signal even if you are uncertain; lower the ratio c. Bias (f): based on personality, expectations, and motivations B. Difference threshold 1. Def: the smallest notable change in a stimulus 2. AKA: just noticeable difference or JND for short, different for each of the senses, but regardless of the sense, it depends on the intenstity of the sense 3. Weber’s Law: the greater the magnitude of the original stimulus, the greater the amount of change required to be detectable a. I/ I = K b. Weight: k= 1/30 C. Sensory Adaptation 1. Defined: when a stimulus is presented continuously at a continuous intensity, sensation of that stimulus is reduced until the individual no longer notices or senses the stimulus- we can achieve the same thing if we present a stimulus very rapidly 2. Why? a.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/17/2008 for the course PSYCH 202 taught by Professor Nezlek during the Fall '08 term at William & Mary.

Page1 / 18

Psych3 - Sensation and Perception October 9 2007 I The...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online