Introduction to Sensation

Learning Targets

1. Contrast sensation & perception.

2. Distinguish between absolute and difference thresholds.

----¨Explain Weber’s Law

Sensation vs. Perception Sensation: our sensory receptors and nervous system receive stimulus from the environment.

Biological!

Perception: The process of organizing and interpreting sensory information, enabling us to recognize it as a meaningful object and/or events Cognitive

Bottom-Up Processing

Your senses (through sensory receptors) send information to your brain

Top Down Processing information processing guided by higher-level mental processes (your brain)...we perceive life based on our experience and expectations

-This cake tastes like coconut

-That man could be a model.

Top-down v. bottom-up processing● Bottom-up processing: senses take in info & relay it to our

brain. Start at bottom (senses) work your way up-you examine each piece of the puzzle w/ your eyes... see the lines, shapes, colors & then make sense of it. ● Top-down processing: uses experiences & our memory to

make sense of what we see,touch, taste, smell & hear - . your brain sees whole words rather than individual letters, you see someone with particular characteristics and stereotype - start at top (brain)

We need top-down processing so we do not have to interpret everything in the world as new.

Bottom-Up vs. Top-Down Processing

Bottom-Up: You rely on your EYES (senses)

Top-Down: You rely on expectations & experiences

Transduction

● process of converting energy from the environment into neural impulses that can be understood by our brains○ receive-energy via specialized receptor

cells○ transform- stimulation into neural impulse○ deliver-send impulse to brain

SensationEach sense has specialized cells- sensory receptors

Selective attention: the focusing of conscious awareness on a particular stimulus ● our senses take in 11 million bits of info per second● your nose is in your line of vision● can you feel your socks now?

Sensation: Cocktail Party EffectCocktail party effect: your ability to attend to only one voice among many, but what happens when you hear your name?

Learning Targets

1. Contrast sensation & perception.

2. Distinguish between absolute and difference

thresholds.

----¨Explain Weber’s Law

Thresholds Absolute Threshold: the minimum stimulation necessary to detect a particular

● light● sound

● pressure● taste

● odor ...(50% of time...VARIES WITH AGE)

¨

https://www.youtube.com/watch?v=IrewnzQYrPI

Signal Detection Theory ¨Predicts how we detect a weak stimulus amid many other stimuli.

¨We detect sensations based on our experiences, motivations, expectations, degree of alertness, and fatigue level● new mom & dad● driving● taster

*Assumes no absolute threshold

Phantom Cell Phone Vibration?!?89% of the undergraduates in the study had experienced these phantom vibrations about every two weeks on the average although only one in 11 classified them as “bothersome.”

http://www.psychologytoday.com/blog/rewired-the-psychology-technology/201305/phantom-pocket-vibration-syndrome

Our body is always in waiting to anticipate any kind of technological interaction, which usually comes from a smartphone. With that anticipatory anxiety, if we get any neurological stimulation, our pants rubbing against our leg for example, you might interpret that through the veil of anxiety, as 'Oh, my phone is vibrating."

Subliminal ● stimulus that is below your absolute

threshold or conscious awareness● items so small that you aren’t consciously

aware that COULD prime your response later

● priming- mostly unconscious activation of certain associations that might predispose one’s perception, memory or response

http://www.youtube.com/watch?v=2NPKxhfFQMs

Difference ThresholdAlso called the JND (Just Noticeable Difference):

¨The minimum difference that a person can

detect between two stimuli. DIFFERENCE between A and B.

*smallest difference in stimulus intensity that a specific sense can detect… The point at which you notice there’s a change

TV volume Change in Stimulus

Weber’s Law

For difference to be noticed must be a constant percentage NOT constant amount

Quick Review

Sensory Adaptation Diminished sensitivity to a sense because of constant stimulation

Perceptual Set

● a mental predisposition to perceive one thing and not another

● seeing a police car TYPE car and perceiving a police car

context effects

● context plays an important role in how we perceive things.

● context (situation) creates a top-down processing because your expectations impact what you perceive

● seeing someone from church at the store and not recognizing them because they are outside the context in which you usually interact

McGurk Effect