Copyright © Allyn and Bacon 2006

Copyright © Allyn and Bacon 2006

Sensation and Perception Chapter 4 Sensation and Perception Copyright © Allyn and Bacon 2007

Copyright © Allyn and Bacon 2006

Copyright © Allyn and Bacon 2006 Sensation An early stage of perception in which neurons in a receptor create an internal pattern of nerve impulses that represent the conditions that stimulated it – either inside or outside the body Or simply… The physical experiences of stimuli Copyright © Allyn and Bacon 2006

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.

Perception The interpretation of our sensations Or simply… A process that makes sensory patterns meaningful and more elaborate Or simply… The interpretation of our sensations Perception draws heavily on memory, motivation, emotion, and other psychological processes to give them meaning.

How Does Stimulation Become Sensation? The brain senses the world indirectly because the sense organs convert stimulation into the language of the nervous system: neural impulses The human mind lacks direct access to the outside world. All external events are filtered through the sense organs and then combined with the individual’s unique mix of memories, emotions, motives, and expectations.

Stimulation  Transduction  Sensation  Perception All the senses…. 1. Transduce stimulus energy into neural impulses 2. Are more sensitive to change that constant stimulus 3. Provide us information about the world Stimulation  Transduction  Sensation  Perception

Copyright © Allyn and Bacon 2006 Transduction The process that converts physical energy, (such as light or sound waves,) into neural messages…the only language the brain understands Receptors Specialized neurons that are activated by stimulation and transduce (convert) it into a nerve impulse Copyright © Allyn and Bacon 2006

Bottom-Up and Top-Down Processing Bottom-Up Processing Analysis that stress features of the stimulus, rather than internal concepts Example: Noticing a flower in a field If your attention is drawn to a flower in a field, it may be simply that the flower is more visually outstanding than the surrounding field….you didn’t have to think about it

Bottom-Up Processing In bottom-up processing, the resulting percept is determined by stimulus features. Color, size, shape…

Bottom-Up and Top-Down Processing --Expectations --Memories --Knowledge --Cultural background --and other cognitive factors ….influence perception

Top-down does not emphasize stimulus features T0p-Down Processing Top-down processing is also known as conceptually driven processing.   Top-down does not emphasize stimulus features

Even though the second letter in each word is ambiguous, top down processing allows for easy disambiguation based on the context.

Top-Down Processing Your dog has been lost for three days, and you cannot stop thinking about him. When you hear a dog bark, you assume that it is your dog.

Figure 6. 1 What’s going on here Figure 6.1 What’s going on here? Myers: Psychology, Ninth Edition Copyright © 2010 by Worth Publishers

Bottom-Up and Top-Down Processing --Expectations --Memories --Knowledge --Cultural background --and other cognitive factors ….influence perception

Bottom-Up and Top-Down Processing --Expectations --Memories --Knowledge --Cultural background --and other cognitive factors ….influence perception

Why Have Attention? Limited resources Attention: Too much information selects important/relevant information

Types of Blindness Inattentional Blindness: Failing to see visible objects when our attention is directed elsewhere. Change Blindness: Failing to notice change in the environment around us.

Cocktail Party Effect Phenomenon of being able to focus one's auditory attention on a particular stimulus while filtering out a range of other stimuli a partygoer can focus on a single conversation in a noisy room. Allows most people to "tune into" a single voice and "tune out" all others. also describes why one may immediately detect words of importance originating from unattended stimuli for instance hearing one's name in another conversation