Sensation and Perception Sensation: your window to the world Perception: interpreting what comes in your window.

What is this? what goes into your eyes is a bunch of blobs, but once you are told that it is a dog, you can organize your thoughts and perceive it as a dog

Bottom-Up vs. Top-Down Processing If a company is run by it’s workers, it would have “bottom-up” management. If a boss runs it, it would be “top-down.” Bottom-up used when you have no prior knowledge = start @ bottom and work your way up. Top-Down used when you have prior knowledge = start @ top & work down (stereotyping) No top down processing = everything new every day!

Top-Down Processing Example I cnduo't bvleiee taht I culod aulaclty uesdtannrd waht I was rdnaieg. Unisg the icndeblire pweor of the hmuan mnid, aocdcrnig to rseecrah at Cmabrigde Uinervtisy, it dseno't mttaer in waht oderr the lterets in a wrod are, the olny irpoamtnt tihng is taht the frsit and lsat ltteer be in the rhgit pclae. The rset can be a taotl mses and you can sitll raed it whoutit a pboerlm. Tihs is bucseae the huamn mnid deos not raed ervey ltteer by istlef, but the wrod as a wlohe. Aaznmig, huh? Yaeh and I awlyas tghhuot slelinpg was ipmorantt! See if yuor fdreins can raed tihs too.

Problems in Processing Prosopagnosia

Psychophysics A study of the relationship between physical characteristics of stimuli and our psychological experience with them. Physical World Psychological World Light Brightness Sound Volume Pressure Weight Sugar Sweet

Thresholds Absolute Thresholds: the minimum stimulation required for us to know that a stimulus has occurred. (at absolute threshold, you will detect the stimulus half of the time (50%)) (example: what is the quietest i can whisper that you will still hear? When you go to the eye doctor and they test your vision, what is the smallest difference in prescriptions that you can see?) Gustav Fechner

Detection Absolute Threshold Intensity No No No Yes Yes Detected Observer’s Response Detected Tell when you (the observer) detect the light.

Signal Detection Theory (SDT) Predicts how and when we detect a faint stimulus (signal) amid background noise (other stimulation). SDT assumes that there is no single absolute threshold and detection depends on: Person’s experience Expectations Motivation Level of fatigue Carol Lee/ Tony Stone Images

SDT Matrix The observer decides whether she hears the tone or not, based on the signal being present or not. This translates into four outcomes. Examples: Decision Pizza Guy Crying Baby Yes No Signal Present Hit Miss Absent False Alarm Correct Rejection Example: tired parents will hear their baby whimpering, but not notice traffic outside. When i moved from champaign to the city, i became much more aware of noises that could have been intruders to my apartment (i’m also more aware of those noises when i’m alone in the apartment)

Subliminal Messages When stimuli are below one’s absolute threshold for conscious awareness. Report in 1956: movie theaters are showing subliminal messages (eat popcorn, drink coca-cola) to manipulate their viewers. (not true)

So, can they get to us???? - we CAN sense stimuli below our absolute thresholds (subliminally, unconsciously) - we CAN be primed to think certain ways we FEEL what we do not know and can not describe.

So, can they get to us???? - we CAN NOT be manipulated to buy stuff. The effect of the subliminal manipulation is very short and subtle – it does not have a lasting effect on people in lab studies. If you flash “eat” at them and show them a restaurant commercial, they’ll be a little hungry for a second, and then forget about it

Weber’s law Ernst Weber- 1795-1878 First quantitative law of psychology There is a constant proportion (not constant amount) between the threshold and the stimulus that can be detected. In order for a change in stimulus to be detected, the amount of change needed depends on the present level of stimulation Explained in terms of proportion:

Difference Threshold Just Noticeable Difference (JND) - the minimum difference between 2 stimuli required for detection 50% of the time. KLEENEX BOXES - : if you are holding a box of kleenex, and i put another box of kleenex on it, you’ll notice the difference. if you’re holding a box of kleenex and i put another piece of kleenex on it, you won’t notice the difference

Selective Attention Your ability to focus your attention on a particular stimulus

Cocktail-party phenomenon The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. Form of selective attention.

Selective Attention Distracted Driving – cell users 4xs more likely to be in accident Inattentional Blindness – failing to see visible objects when your attention is directed elsewhere Change Blindness - failing to notice changes in the environment

Think of an experience where you were so caught up in the activity that you missed something obvious in the environment? The environment was so distracting that you couldn’t concentrate. ADHD seem to lack the ability to be selectively attentive – focus on unimportant stimuli don’t filter it out – interferes with processing information

Sensory Adaptation Decreased responsiveness to stimuli due to constant stimulation. Do you feel your underwear all day?

FRQ Practice Point Marisol is planning a ski trip for spring break. Define absolute threshold and difference threshold, and explain how each one might play a role in her perception of the winter weather she will experience.

Influences on Perception Perceptual Set a mental predisposition to perceive one thing and not another Expecting certain results though experience.

What do you see?

SCHEMAS our perceptual set is developed through schemas, the concepts that we form through experiences. They help us organize our perceptions. If an atheist or Buddhist saw that wall, they’d probably see nothing. A devout Christian would be more likely to see virgin Mary. Branding  French fries from McDonalds vs. no name Gender roles  is the baby a boy or girl?

FUN with Perceptual Sets -Our EXPERIENCE shapes our perceptions

FUN with Perceptual Sets -Our EXPERIENCE shapes our perceptions

FUN with Perceptual Sets -Our EXPERIENCE shapes our perceptions

Context Effects

Extrasensory Perception Telepathy – mind reading Clairvoyance – perceiving remote events Precognition – Knowing things before they happen Telekinesis (psychokinesis) – moving objects with one’s mind (not technically ESP) PARAPSYCHOLOGY … Ghostbusters opening