Sensation and Perception

QUICK REVIEW:

Sensation:  YOUR WINDOW TO THE WORLD

Perception:  INTERPRETING WHAT COMES IN YOUR WINDOW

Sensation:  The processes by which our sense organs receive information from the environment

Perception:  The processes by which people select, organize, and interpret sensations

Basic Definitions:

• Sense: Physical system that receives physical stimulation from surrounding environment and translates that stimulation into an electrochemical message
• Sensation: Detecting physical energy in environment and encoding it as neural signals. Neurons transmit the information from the sense organ to the brain
• Perception: Processing of information done by the brain – mental processes that organize and interpret sensory information that has been transmitted to the brain.

The Cognitive Approach emphasizes that people differ from each other because individual perceptions and thought processes are different.  Sensation and perception in psychology is understanding how our senses work and how we perceive stimuli in the environment.

Sensation:

• Input of sensory information
• Process of receiving, converting, and transmitting information from the outside world

Sensory Systems:

Vision:  The most studied of all the senses

• Light enters through the pupil and reaches the lens which focuses light on the retina
• The rods and cones convert the light energy into electrical impulses which then travel over the optic nerve to the brain

Hearing:  The auditory nerve carries impulses from the inner ear to the brain, resulting in the sensation of sound

Parts of the Ear:  Ear canal, eardrum, malleus(hammer), incus(anvil), stapes(stirrup), cochlea, and the auditory nerve

Smell and Taste:  The Chemical Senses

SMELL:  The chemical molecules on odor reach the odor receptors in the upper passages of your nose. These receptors convert chemical sensations into nerve impulses through the olfactory nerve to the brain.

TASTE:  Taste receptors or taste buds are on the tongue. There are four basic tastes:  sweet, sour, salty, and bitter

TOUCH:  THE SKIN SENSES

At least four kinds of sensations you get through your skin:

•       Pressure
•       Warmth
•       Cold
•       Pain

Vestibular Sense (sense of balance):

• Kinesthetic Sense (did you eat to much, do you have a headache?
• Kinesthesis sensors in the muscles, tendons, and joints which control body movement, without this one would have to watch their feet as they walked!

Where do these “Senses” Happen?  The Brain!

• The physical energy in the environment is detected by the eyes, ears, etc. but we can’t see, hear, etc. until the brain interprets them. So in a way, we see, hear, smell, etc. in our brains!

• Neural impulses from sensory receptors in our eyes, ears, skin, & other sensory organs create neural messages sent to various areas of our brain.

Translation = Transduction = Communication between the brain and the body and between different regions of the brain occurs via neuron

• Communication between neurons occurs electrochemically. Within neurons = electrical, between neurons = chemical creating the brain’s “language” is electrochemical
• All senses involve receptor cells. Receptor cells transduce (translate) physical stimulation and energy from the environment into electrochemical messages that the brain can understand.

Transduction: Translating messages into the brain’s language

• Sense orgrans transduce sensory energy into neural (bioelectrical) energy
• Converting one type of energy into another type is the process of transduction
• Your brain only deals with bioelectrical impulses so transduction must occur; what cannot be transduced cannot be a stimulus

Sensation & Perception Processes

• Sensation: is what occurs when a stimulus activates a receptor
• Sensation + Experience= Perception
• Perception: The brain receives information from the senses and organizes and interprets it into meaningful experiences

Sensory Limits: How strong must the message (signal) be for it to be detected by the sensory receptor?

• Absolute thresholds
• Difference thresholds
• Sensory adaptation and habituation
• Study of these sensory limits and phenomena is called “Psychophysics”

PERCEPTUAL PROCESSING:

• Top-Down: Perception is guided by higher-level knowledge, experience, expectations, and motivations
• Top-Down Processing: Information processing starting “at the top” with higher-level processes and then working down

• Bottom-Up: Perception consists of recognizing and processing information about the individual components of the stimuli
• Bottom-Up Processing: Information processing beginning “at the bottom” with raw sensory data” sent “up” to the brain for higher-level analysis

Perceptual Interpretation – A Perceptual Set

• A mental predisposition to perceive one thing and not another
• This is based on experiences, assumptions and expectations.

What shapes our perceptual sets?

• What things do you think might affect our perceptual sets (i.e., our tendency to perceive things in certain ways)?
• Context effects
• Past experiences
• Effects of our culture

Perceptual Set –  Context Effects

The same physical stimulus can be interpreted differently depending on perceptual set, e.g., context effects.

When is the middle character the letter B and when is it the number 13?

Perceptual Set:  Interpretation

• What is seen in the picture depends on the order and direction one looks at the figures, look at the next picture from LEFT to RIGHT

SELECTIVE ATTENTION:

We can only pay attention to one aspect of one object at a time – 

DO NOT TAKE YOUR EYES OFF OF THE PLAYERS WEARING WHITE

Extrasensory Perception – (ESP):

• Telepathy: Mind-to-mind communication. One person sending thoughts and the other receiving them.
• Clairvoyance: Perception of remote events, such as sensing a friend’s house on fire.
• Precognition: Perceiving future events, such as a political leader’s death.

• Perception without sensory input is called extrasensory perception (ESP). A large percentage of scientists do not believe in ESP

An “alleged” perception

References:

Bernstein, D.A. & Nash, P.W. (2008). Essentials of psychology (4th ed.) Boston: Houghton Mifflin Company.

Feldman, R. (2013). Essentials of understanding psychology (11th ed.). New York, NY: McGraw-Hill.

Friedman, H.S. & Schustack, M.W. (2012), Personality: classic theories and modern research (5th ed). Boston: Pearson Allyn & Bacon.

McGraw-Hill.McGraw Hill Higher Education (2013), The McGraw Hill Companies, Inc.

Ryckman, R. M. (2013). Theories of personality (10th ed.). Mason, OH: Cengage Learning.