Cornell Psych 205: day06

8/14/2019 Cornell Psych 205: day06

1/54

Psychology 205

Perception

06 Feb 03

Day 06


2/54

Three Kinds of Adaptation

definition: "Modify to suit new conditions"

biology: Darwin -- change in the genome so that the phenomebetter fits its ecological niche; better --> reproduction;change random with selection

perception:1. Responding to constant stimuli

sensory neurons2. Accommodating different ranges of stimulation

sensory systems3. Accommodating different patterns of stimulation

cortex


3/54

1. Response to constant stimuli neuronal

touch, olfaction, gustation, visionnot audition, pain, or kinesthesis

response decrement, spontaneous recovery

cross-adaptationadaptation (d') vs. habituation ()

stabilized imagesPurkinje's tree

saccades & fixationspursuit movementsphysiological nystagmus (eye tremors)


4/54


5/54

slowlyadapting

rapidlyadapting


6/54

for conveniencelook at rapidlyadapting systems


7/54


8/54

how to test?


9/54

one testinterval


10/54

2nd testinterval


11/54

3rd testinteval


12/54

Result byconnectingdata points


13/54

no cross-adaptation

adapt withone stimulus

test with adifferentstimulus


14/54

some crossadaptation


15/54

adaptation (d')change in the sensitivityd' decreases with increased neural

adaptation but adaptation is not the only cause for a change in d'

habituation ()change in ones bias;

possible increase in boredom,or simply tuning out


16/54

stabilized images ----->Purkinje's tree

3 basic eye movements

1. saccades & fixations: endogenous control

2. pursuit movements: exogenous control

3. physiological nystagmus eye tremors, automatic,uncontrolled


17/54

eye movements

1. saccades & fixations:3-4/s in reading, watching cinema, often less elsewhere

fixations ~200-300 ms; saccades ~50-100 mssaccades up to 600 /s

2. pursuit movements:up to 80/s, lowered acuity (tracking not perfect)

3. physiological nystagmusup to 150 cycles/s; amplitude = half diameter of cone


18/54

classicalmethod


19/54


20/54

Process of perception:

1. One sees the content of the slide perfectly2. Then content fades3. Then content fades to neutral gray, not black


21/54

Approximation:

stare atblack dot

overtimerings

willfade


22/54


23/54

alternativemethod, notquite asgood


24/54

Stabilized edges (Krauskopf, 1963)

Filling in of color, despitethe fact thatthe receptorsarestimulateddifferently

Importanceof edges!


25/54

Are there any stabilized images inthe real world of our natural experience?


26/54

9 of 10 photons enteringthe eye are absorbedbefore nearing thereceptors; many receptorsare beneath blood vessels

and arteries


27/54

Purkinjes

tree

optic diskfovea


28/54

2. Accommodating different ranges of stimulationsensory systems

light & dark adaptationphotopic & scotopic cones & rodsmesopic

ossicular dampening

signal-to-noise ratiosoptimality in sensory systems


29/54

light & dark adaptation:light --> quick; dark --> slow

two light-catching systems

photopicday vision, color, cones

scotopicnight vision, black and white, rods ~500 times as sensitive after complete dark adaptation

mesopic both, room light


30/54


31/54

Is there an analog in audition?

partial

ossicular dampening


32/54

Ossiculardampening causedby muscles aroundossicles

When in the midst of constant loudnoise, they clench and dampen the

sound by about 6 dB, ~3x


33/54

Why not simply build a supersensitive system?avoid the necessity of needing two (or more) systems


34/54

1. Range of neural spikes/unit time is relatively small maximal firing = 1000 s

2. The system should avoid firing near maximal ratefor too long. Possible tissue damage; ossicular dampening.


35/54

3. Accommodating different patterns of stimulationcortical

re-learning usingMolyneux's paradox in animals and humans

Roger Sperryneural regeneration in amphibians

George Stratton, Ivo Kohler, and others inverting lenses body schema


36/54

William Molyneux, Dioptrica Nova, 1692

Molyneuxs Paradox - the orientation of thevisual fieldRelevant to M ller VIII

Molyneuxs Premise - depth perception

Moylneuxs Conjecture - the blind given sight


37/54

upside downand backwards;rotated 180


38/54

Neuroplasticity and behavior

Roger Sperry


39/54

rotate the eyes

upside down,backwards,depth wrong


40/54

switchopticnerves


41/54


42/54

Snyder &Pronko

Dolezal


43/54

In responseto Molyneux


44/54

upside down;

swinging;coordination


45/54

gradualimprovement


46/54

still moreimprovement;

left-right;swinging


47/54

gradual build up of unifiedsense of body and sight


48/54

Ivo Kohler

after a 30-day period of adaptation toinverting lenses


49/54

Ivo Kohler

after a 30-day period of adaptation toinverting lenses

able to drive a Vespa rapidly, weaving in an out of traffic, indowntown Innsbruck


50/54


51/54

slow adaptation to new state of affairs;old schema suppressed, not changed


52/54

wedgeprisms

sensorimotoradaptation


53/54

people adapt;chicks dont

adaptation to spatialinversion anddisplacements are cortical,and beyond V1


54/54

Three Kinds of Adaptation

definition: "Modify to suit new conditions

biology:

perception:1. Responding to constant stimulisensory neurons --> Purkinjes tree & lab phenomena

2. Accommodating different ranges of stimulationsensory systems --> light/dark adaptation

ossicular dampening3. Accommodating different patterns of stimulation

cortical --> inverting & wedge lenses

Cornell Psych 205: day06

Documents

Transcript of Cornell Psych 205: day06