Upload
shima
View
21
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Sensation & Perception. A.P. Psychology Chapter 4. Drill 1-12-2010. Read the case of Dr. P….. What accounts for his inability to recognize faces and familiar objects by sight? How would your world be different if you were unable to sense the objects & people around you? - PowerPoint PPT Presentation
Citation preview
Sensation & Perception
A.P. Psychology
Chapter 4
Drill 1-12-2010
• Read the case of Dr. P…..
• What accounts for his inability to recognize faces and familiar objects by sight?
• How would your world be different if you were unable to sense the objects & people around you?
• Give examples of how your life would change if you were to lose your sense of sight?
Visual Agnosia
• The inability to recognize objects through sight
• The person’s eyes function properly, but there seems to be a problem with the processing of what is being seen
• Seems to be the result of damage somewhere in the visual pathway
Sensation & Perception
• Sensation• The stimulation of the
sense organs• Involves the
absorption of energy, such as light or sound waves by sensory organs
• Perception• The selection,
organization, and interpretation of sensory input
• Involves translating sensation into something that is meaningful
What do you see?
Psychophysics
• The study of how physical stimuli are translated into psychological experience– Gustav Fechner (1860’s) – German
– Sensation begins with a Stimulus» Any detectable input from the
environment– Wanted to know - For any given sense, what
is the weakest detectable stimulus?
Thresholds
• Threshold ~ a dividing point between energy levels that do and do not have a detectable effect
• Absolute Threshold ~ for a specific type of sensory input is the minimum amout of stimulation that an organism can detect
• Define the boundaries of an organism’s sensory capabilities
Examples of Absolute Thresholds
Vision A candle flame seen at 30 miles on a dark clear night
Hearing A tick of a watch under quiet conditions at 20 feet
Taste One teaspoon of sugar in two gallons of water
Smell One drop of perfume diffused into entire the entire volume of a six-room apartment
Touch The wing of a fly falling on your cheek from a distance of 1 centimeter
The Just-Noticeable Difference
• The smallest difference in the amount of stimulation that a specific sense can detect
• Similar to absolute thresholds – absolute thresholds are the JND from no stimulus input
• Smallest detectable difference is a fairly stable proportion
• Ernst Weber • Fechner’s brother-in-law• First to demonstrate the JND• Weber’s Law ~ the size of a JND is a constant proportion
of the size of initial stimulus (Weber’s fraction)» Ex. The Weber fraction for lifting weights is
approximately 1/30 which means that you should be able to detect the difference between 30 ounce weight & 31 ounce weight, but not a 90 & 91 ounce weight (difference is 3 ounces for 90)
Fechner’s Law• States that the magnitude of a sensory
experience is proportional to the number of JND’s that the stimulus causing the experience is above the absolute threshold
• Constant increments in stimulus intensity produce smaller & smaller increases in the perceived magnitude of sensation
» Ex. You are in a dark room with a single lamp that has 3 bulbs of the same wattage. You turn a switch and one bulb lights. After a dark room, the difference is striking. Turn again, and a second bulb comes on. The amount of light is doubled, but the room does not seem twice as bright. And so on….
Homework
• The Secret Life of James Thurber ~ Article & Questions
• Sensation & Perception Passage