This document provides an overview of sensation and perception. It discusses how sensation is the process of receiving stimulus energies from the external environment through sensory organs like the eyes, ears, skin, tongue and nose. Perception is described as the process of organizing and interpreting sensory information to give it meaning. Sensory receptors detect and transmit stimulus information to the brain. The document outlines concepts like sensory thresholds, habituation, adaptation and top-down and bottom-up processing. It provides examples of absolute and difference thresholds for different senses.

1. SENSATION
AND
PERCEPTION

5. Sensation and Perception
I. Detecting, Processing and
Interpreting Experiences
II. Sensory Receptors
III. Sensory Thresholds
IV. Habituation and Sensory
Adaptation
V. The Sensory Organs
VI. Perceiving Sensory Stimuli

6.  SENSATION
the process of receiving
stimulus energies from the
external environment
- sensory organs:
eyes (visual system)
ears (auditory)
nose (olfactory)
tongue (gustatory)
skin (tactile)

7.  PERCEPTION
the process of
organizing and Prior experiences
interpreting Expectations
sensory Memory
information to Biases
give it meaning.

8. Why is it important to study
sensation and perception?
The purpose of perception is:
1) to represent information from the
outside world internally;
2) adaptation that improves a species’
chances for survival; and
3) to help in designing devices to
restore perception to those who have
lost some (or all) and also to devise
treatments for other perceptual
problems.

9. Have you ever experienced
(or seen someone) bumping
into a clear window glass
because you did not know that
it was there?

10.  BOTTOM-UP PROCESSING
- Sensory receptors register information
about the external environment and
send it up to the brain for analysis and
interpretation.
 TOP-DOWN PROCESSING
- Starts out with cognitive processing at
the higher levels of the brain.
- Cognitive processes include knowledge,
beliefs and expectations.

11. JIGSAW PUZZLE

12. SENSORY RECEPTORS
 All sensation begins with sensory
receptors.
 Sensory receptors are specialized cells
that detect and transmit stimulus
information to sensory nerves and the
brain.

13. SENSORY THRESHOLDS
 Buzzing mosquito?
 Difference between regular Coke and
Coke Zero?

14. SENSORY THRESHOLDS
 Absolute threshold
- Minimum amount of energy that a
person can detect
 Difference threshold
- just noticeable difference (jnd)
- the degree of difference that must exist
between two stimuli before the difference
is detected.

15. SENSORY THRESHOLDS
 Absolute Threshold
- Orange juice
- One tablespoon?
- Two tablespoon?
- Three tablespoon!
- Watching TV while your roommate is
sleeping.
- Volume?

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17. Approximate Absolute
Thresholds
 Vision
- A candle flame at 30 miles on a dark, clear night.
 Hearing
- A ticking watch at 20 feet under quiet conditions.
 Smell
- One drop of perfume diffused throughout 3 rooms
 Taste
- A teaspoon of sugar in 2 gallons of water
 Touch
- The wing of a fly falling on your cheek from a
distance of one centimeter.

18.  Difference Threshold
- Watching TV while your roommate is
sleeping.
- Your roommate, suddenly wakes-up.
- Also wants to watch the TV!
- Volume?

19. JND!
No JND!
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20.  A student late for his class.
10: 03 – late?
10:05 – late?
10: 10 – late?
10:15 – late!!!
It takes 15 minutes for a student to be
detected as late.
Absolute or difference threshold?
*Depends on the individual who perceives
and the condition of the environment.

21.  Subliminal Perception
- the ability to detect information below
the level of conscious awareness.
- JAMES VICARY (1957)
- “Eat Popcorn”; “Drink Coke”
- .003 second once every 5 secs.
- The sales of popcorn and coke
increased!
- HOAX!
- Subliminal perception does not work in
advertising.

22. HABITUATION AND SENSORY
ADAPTATION
 The lower centers of the brain sort through
sensory stimulation and “ignore” or
prevent conscious attention to stimuli that
do not change.
 Sound of aircon
 Smell of garbage
 Reading your readings?

23.  Sensory adaptation
- The sensory receptor cells become less
responsive to an unchanging stimulus.
- The receptors are no longer sending
signals to the brain.
 Habituation
- The sensory receptor cells are still
responding to the stimulus, but the
lower centers of the brain are not
sending the signals from those
receptors in the cortex.

24. QUESTIONS?