Sensation

Sensation Information coming into our brain from our sensory receivers

Scientific Names for the Six Senses•Seeing: Visual•Hearing: Auditory•Tasting: Gustatory•Smelling: Olfactory•Sense of Touch: Tactile•Balance: Vestibular

Bottom-up Processing

Analysis of the stimulus begins with the sensory receptors and works up to the level

of the brain and mind.

Letter “A” is really a black blotch broken down into features by the brain that we perceive as an

“A.”

Top-Down Processing•Information processing guided by

higher-level mental processes as we construct perceptions, drawing on our experience and expectations.

•Top Down Processing explains how our expectations and prior experiences guide our perceptions.

THE CHT

Top-Down Processing

•Aoccdrnig to rscheearch at Cmabrigde

Uinervtisy, it deosn't mttaer in waht oredr

the ltteers in a wrod are, the olny iprmoetnt

tihng is taht the frist and lsat ltteer be at the

rghit pclae. The rset can be a total mses and

you can sitll raed it wouthit a porbelm. Tihs

is bcuseae the huamn mnid deos not raed

ervey lteter by istlef, but the wrod as a

wlohe.

How many faces do you see?

Making Sense of Complexity

“The Forest Has Eyes,” Bev Doolittle

Psychophysics

•Psychophysics: study of the relationship between physical characteristics of stimuli and our psychological experience of them

▫Light - brightness▫Sound - volume▫Pressure - weight▫Taste - sweetness

Thresholds

Absolute ThresholdMinimum stimulation needed to detect a particular stimulus 50% of the time.Subliminal MessagesMessages presented below absolute thresholds – not consciously perceived

http://www.youtube.com/watch?v=73fCLx-mFLg

“Subliminal Messages”

•Some have argued that humans still “pick up” these messages that influence our “unconscious.” Do these messages have suggestive powers?

•Skeptics argue “Subliminal Messages” are heavily influenced by top down processes.

•Example: Feeling “hungry” during subliminal advertisements.

Difference ThresholdAmount of change needed to notice that a change has occurred.

Weber’s Law: The greater or stronger the stimulus, the greater the change required to notice that a change has occurred. The two stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different.

Sensation: Thresholds•Signal Detection Theory: predicts how and

when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

•Assumes that there is no single absolute threshold because the idea of a threshold ignores the decision-making ability of the test subject.

Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation.

Put a band aid on your arm and after awhileyou don’t sense it.