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Psych 2 - Sensation and Perception
Psychology (PSYC 101)
Queensborough Community College
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Sensation and Perception
Sensation: the sense receptors - How sense receptors and the nervous system represent the external environment Perception: what the brain does with information - Mentally organizing and interpreting information. ◦ The brain interprets in large parts based on pervious experiences
Studying Sensation: Psychophysics - Relation between the physical aspects of stimuli an our experience to them. - We see some but not all types of light ◦ We are unable to see infrared light - If we could see infrared light, we would not need light goggles. Psychophysical Issues: - Absolute threshold ◦ The minimum amount of energy in a sensory stimulus to detect it (50% of the time). - A candle flame can be seen on a mountain at distance of 30 miles on a dark night with no other lights present. - Difference threshold ◦ Minimum difference between two sensory stimuli detected (50% of the time) - Weber's law states that a just noticeable difference is a constant proportion of the intensity of an initial stimulus
- It is easier to detect a quiet noise in a quiet house than a quiet noise in a loud house.
- To detect a sound in a loud house, the intensity would have to be greater.
- Sensory adaptation ◦ Diminishing sensitivity (or less sensitivity) to an unchanged sensory event --> get used to something they doesn’t changed. ◦ Our senses are designed to notice change ◦ We seldom notice:
- Wristwatch
- Shoes on our feet
- Jewelry we are wearing
Psychophysical Measures: - Studying sensation 1. Absolute Threshold 2. Difference Threshold 3. Sensory Adaption
Structures of the eye: Pupil - Small opening through which light enters Iris - Regulates the size and the amount of light Lens - Focuses the incoming rays by changing the curvature of the eye Retina - Light sensitive surface of eye - Converts light energy into neural impulses (chemical information)
- Occurs after 10 minutes for cones, but 20-30 minutes for rods.
- Light adaption occurs faster for rods and cones
Perceptual constancy and illusion: From "Chaos" comes "order" - Maintaining a stable internal representation even when the physical stimulus is changing. ◦ Brightness constancy ◦ Shape constancy ◦ Size constancy ◦ Color constancy This is all processed in the brain
- Illusion physical stimuli that consistently produce errors in perception
Bottom-up or Top-Down Processing Bottom-up - Extract or remove information at the level of the stimulus Top-Down - Expectations guide processing of information - Experience driven
Gestalt view of perception Pragnantz principle Visual elements are grouped in the simplest way possible
Continuity principle - Visual elements are seen as continuous Closure principle - Incomplete figures are seen as complete Proximity principle
- Objects close together are grouped together Similarity principle
- Like objects are grouped together
Perceiving dept: distance ---one of the most complex perceptual abilities Product of binocular and monocular cues The closure an object is to the head the more different is the image received by each eye
Psych 2 - Sensation and Perception
Course: Psychology (PSYC 101)
University: Queensborough Community College
