PSYCH Ms. Shirley UNIT 2

Biological Bases of Behavior

SENSATION & PERCEPTION

INTRODUCTION

DO NOW QUESTION: 

Are you influenced by advertisements -

tv, radio, print, billboard, internet?

Over the past decade--from 2001 to 2010--Apple ranks number two as far as product placements go, its products having appeared in 112 of the number one movies of the period. Ford, with 144 placements, beats them out.

See Brand Channel's graph of Apple's history of movie placements below:

Reese's Pieces, E.T.After the bite-sized candies appeared

in Steven Spielberg's 1982 movie E.T., sales shot up between 65% to 200%, and the underdog candy from Hershey's became a competitor to Mars' M&M's. And by modern product placement standards, Hershey's barely had to pay a cent for it.In fact, Mars turned down the

opportunity to have M&M's appear in the movie, so Hershey's eagerly agreed – and got Reese's Pieces placed in the feature film for free. All the company had to do was contribute $1 million in advertising for tie-ins, a bargain considering all the free publicity and increased revenues that resulted.

Sensation

SensationProcess by which our sensory receptors & nervous system receive stimulus from the environment

Essentially the stimulation on the sense organs

PerceptionProcess of organizing & interpreting sensory information, enabling us to recognize meaningful objects & events.

★ Selection★ Organization★ Interpretation

of sensory input

What if we could sense everything?Life would hurt.

So we can only take in a window of what is out there.

This is the study of psychophysics: relationship between physical stimuli and our psychological experiences to them.

Bottom-Up ProcessingAnalysis that begins with the sense

receptors and works up to the brain’s integration of sensory information. You begin by examining small details and piece them together into a larger picture.

Top-Down ProcessingInformation processing guided by

higher-level mental processesAs when we construct perceptions

drawing on our experience and expectations

Processing Sensation

Sax?Or ‘saxy’

lady? Which line is longer?Really?

PEOPLE?or

TOWERS?

Psychophysics: quantitatively investigates the relationship between physical stimuli & the sensations & perceptions they affect

Fechner - coined the term; making connections between matter & mind; public & private

Wundt - structuralism

Weber - signal detection theory

Light: brightnessSound: volumePressure: weightTaste: sweetness

Absolute Threshold

For a specific type of sensory input, it is the minimum stimulus intensity that an organism can detect.Absolute thresholds are anything but absolute. When stimulus intensity increases, so does the subjects’ probability of responding to stimuli gradually increases.

*The minimum stimulation needed to detect a stimulus 50% of the time.*

Difference ThresholdMinimum difference that a person can detect between 2 stimuli required for detection 50% of the time.

JND - Just Noticeable Difference -- smallest difference in stimulus intensity that a specific sense can detect.

We have a very sensitive absolute threshold for vision:Only 3 photons on single receptor across a moment of time will trigger a detection

Our other modalities are sensitive, though chemically we have nothing over sharks:

Sharks can detect a single drop of blood in thousands of gallons of water Whereas we can taste a teaspoon of sugar in only 2 gallons.

YouTube: Gestalt in Sensation & Perception

Signal Detection TheoryPredicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise).Assumes that there is no single absolute threshold.

We detect stuff based on our experiences, expectations, motivations & fatigue level.

Sensation ThresholdsWeber’s Law - to perceive as different, 2 stimuli must differ by a constant minimum percentage.

light intensity- 8%weight- 2%tone frequency- 0.3%

Sensory Adaptation - diminished sensitivity as a consequence of constant stimulation.

Weber’s LawTo perceive a difference between 2 stimuli, they must differ by a constant percentage; not a constant amount.

Example: Weber found that the JND between 2 weights was approximately proportional to the mass of the weights. Thus, if 105g can be distinguished from 100g, the JND is 5g. If the mass is doubled, the differential threshold also doubles to 10g, so that 210g can be distinguished from 200g.

Weber’s Law ExperimentWeber’s law: Difference thresholds grow with the magnitude of the stimulus, because the difference is a percentage of the magnitude of the stimulus, not a constant amount.

What are a few examples of Weber's principle in your everyday life?

Weber’s Law ExperimentTry the following experiment: 2 envelopes, one with two quarters in it, one without any quarters.The subject will be able to tell the difference.However, put the envelopes in a pair of shoes and try to tell the difference.

Weber's Principle: difference thresholds grow with the magnitude of the stimulus

Weber’s Law In PracticeIf you make $5 an hour a 25 cent hour raise will be noticeable.But at $10 an hour you may need 50 cents to really realize a difference.

In car sales, after the sale customer won’t really notice $500 stereo.

After drinking tea with lemon, a grapefruit will not taste as sour… but after a roll, it will taste especially sour.

After holding salty water in mouth, it will taste less salty, and drinking fresh water afterwards, it will taste sweet.

Subliminal StimulationBelow one’s absolute threshold for conscious awareness.

Yes & No

Slide studies showed some emotional reactivity (called priming a response).

The effects are subtle and fleeting.

Are subliminal ads effective?

2000 US Presidential Campaign Ad

YouTube: 2000 US Presidential Campaign Ad - Uses Subliminal

Selective AttentionThe focusing of conscious awareness on a particular stimulus.

Selective Attention:The Cocktail Party Effect

Ability to listen to 1 voice among many

Our auditory system separates the input into distinct auditory

channels.

Sensory AdaptationDiminished sensitivity as a result of constant stimulation.

We don't really detect physical energy

Our senses are more evolved to detect changes in physical energy

If there are no changes in our physical environment, we adapt to the static energy levels & cease to notice them: This is sensory adaptation.

We do not perceive the world how it really is, but as it is useful for us to perceive it.

Advertising ExecsGrocery Store ExecPeople are VERY Predictable

Dubbed a ‘psychological illusionist’ by the Press, Derren Brown is a performer who combines magic, suggestion, psychology, misdirection & showmanship in order to seemingly predict & control human behaviour, as well as performing mind-bending feats of mentalism.

For the past ten years Derren has created TV and stage performances that have stunned audiences, debunked the paranormal & encouraged many to improve and enhance their own mental abilities.

His first show appeared in 2000, Derren Brown: Mind Control, and followed with Trick of the Mind, Trick or Treat & a series of Specials including the controversial Russian Roulette & the hugely popular Events.

YouTube: Derren Brown: "Appearance & Reality"

In his book Tricks of the Mind, Brown writes,

"I am often dishonest in my techniques, but always honest about my dishonesty. As I say in each show, 'I mix magic, suggestion, psychology, misdirection and showmanship'.

I happily admit cheating, as it's all part of the game. I hope some of the fun for the viewer comes from not knowing what's real and what isn't.

I am an entertainer first and foremost, and I am careful not to cross any moral line that would take me into manipulating people's real-life decisions or belief systems."