1. Sensation and Perception Unit 7
Psychology
Sensation and Perception
Mr. Fuller

2. The Basics
We do not actually experience the world directly, but instead we experience it through a series of “filters” we call senses.
The study of these sense and their effect on our behavior is called sensory psychology.

3. Sensation
Sensation: The process by which a stimulated receptor (eyes, ears…) creates a pattern of neural messages that represent the stimulus in the brain, giving rise to our initial experience of the stimulus.

4. Our Senses
You will notice that all of our sense organs are very much alike.
They all transform physical stimulation (such as light waves or sound waves) into the neural impulses what give us sensations (such as light and dark).

5. Perception
Perception: A mental process that elaborates and assigns meaning to the incoming sensory patterns.
Perception creates an interpretation of sensation.
Do you see faces or vases?

6. Sensation and Perception
Perception is essentially an interpretation and elaboration of sensation. Therefore, sensation refers to the initial steps in the processing of a stimulus.
These pictures look fairly similar

7. The True Picture

8. The Famous Mona Lisa…Frown or Smile

9. The Famous Mona Lisa…Frown or Smile

10. Big Idea
Although it seems the brain interacts directly with the outside world, it does not.
The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural messages.
In short, the brain never receives stimulation directly from the outside world.

11. Transduction: Changing Stimulus to Sensation
In all the sense organs, it is the job of sensory receptors to convert incoming stimuli information into electrochemical signals—neural activity.
Transduction: The sensory process that converts energy, such as light or sound waves, into the form of neural messages.
Transduction with Hearing

12. The neural impulse carries a code of the sensory event in a form that can be further processed by the brain.
Light Waves
Neural Signals

13. Notes Sensation and Perception
Stimuli – detectable inputs from the environment
Sensation – stimulation of sense organs
Perception - the selection, organization, and interpretation of sensory input
What is the difference?
Perception involves organizing and translating sensory input into something meaningful. (rose example)
Psychophysics – study of how physical stimuli are translated into psychological experiences

14. Notes Continued
Thresholds – dividing point between energy levels that do and do not have a detectable effect.
Absolute threshold – minimum amount of input required to produce a sensation (pencil poke)
Difference threshold or JND, just noticeable difference– minimum amount of input to produce a change in sensation (perceived changes, weights, sweetness, etc…)
Weber’s Law – larger (or stronger) the stimulus the larger the change required
Subliminal – Latin for below threshold
Debatable effects (see bottle ad)

16. Notes Continued
Signal detection theory – detection of stimuli involves decision and sensory processes, which are both influenced by a variety of factors besides stimulus intensity. Influence of cognitive activity

17. Sensory adaptation Senses respond best to changes
Refers to gradual decline in sensitivity to prolonged sensation

18. Perceptual Constancies
Tendency to experience a stable perception in the face of continually changing sensory input.
Along with depth cues, and visual organization, helps us perceive the world accurately. (brain makes sense of the inputs and surroundings, ex. Size of people approaching us. Are they growing in size?)
Optical illusions: discrepancy between the appearance of a visual stimulus and its physical reality.

19. Optical Illusion Examples
Color blind test – write the number you see. How many people in see something different or nothing at all?
Snakes – shift your focus around the image. What happens?
Red diamonds – stare at the image, shift your focus around the image. What happens? Try this at several distances.
Fluff – this one takes about a minute to really work. Stare at the black dot. What happens to the colorful fluff?
Four rings – stare at the dot and change your distance from the image (lean back and forth… ) What happens?
What causes these optical illusions