心理学与生活-第28章

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1。　Depth　perception　requires　that　the　visual　system　extract　three…
dimensional　representations　from　two…dimensional　information　
2。　Vision　relies　on　depth　cues　that　allow　the　interpretation　of　sensory　
input　
G。　Binocular　and　Motion　Cues　
1。　Binocular　disparity　is　the　displacement　between　the　horizontal　
positions　of　corresponding　images　in　the　two　eyes　
2。　Convergence　is　the　turning　in　of　the　eyes　when　they　fixate　on　a　single　
object。　The　eyes　must　converge　more　for　objects　that　are　near　than　for　
objects　that　are　distant。　
3。　Relative　motion　parallax　provides　information　about　depth　as　an　
individual　moves　because　objects　that　are　close　appear　to　move　more　
than　objects　that　are　farther　away　
H。　Perceptual　Constancies　
1。　Perceptual　constancy　refers　to　the　tendency　to　see　the　world　as　invariant；　
constant；　and　stable；　despite　changes　in　the　stimulation　of　sensory　
receptors　
2。　Size　and　shape　constancy　
a）　Size　constancy　refers　to　the　ability　to　perceive　the　true　size　of　an　
object　despite　variations　in　the　size　of　its　retinal　image　

b）　Shape　constancy　refers　to　the　ability　to　perceive　correctly　an　
object’s　actual　shape；　even　when　the　object　is　slanted　away　
from　the　viewer；　making　the　shape　of　the　retinal　image　
substantially　different　from　that　of　the　object　itself　

c）　Orientation　constancy　refers　to　the　ability　to　recognize　the　true　
orientation　of　the　figure　in　the　real　world；　even　though　its　
orientation　in　the　retinal　image　is　changed　

d）　Lightness　constancy　is　your　tendency　to　perceive　the　whiteness；　
grayness；　or　blackness　of　objects　as　constant　across　changing　
levels　of　illumination　

IV。　Identification　and　Recognition　Processes　
A。　Bottom…Up　and　Top…Down　Processes　
1。　Bottom…up　processing　is　taking　sensory　data　into　the　system　and　
sending　it　upward　for　extraction　and　analysis　of　relevant　information。　
It　is　anchored　in　empirical　reality　and　deals　with　bits　of　information　
and　the　transformation　of　concrete；　physical　features　of　stimuli　into　
abstract　representations。　Also　called　data…driven　processing。　
2。　Top…down　processing　is　when　past　experiences；　knowledge；　
motivations；　cultural　background；　and　expectations　affect　perception；　
as　higher　mental　functioning　influences　how　objects　and　events　are　
understood。　Also　called　hypothesis…driven　processing。　
3。　Phonemic　restoration　occurs　when　there　are　gaps　in　physical　signals　
and　perception　replaces　part　of　a　word　that　was　obscured　by　noise　in　
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a　very　loud　environment　

B。　Object　Recognition　
1。　Irving　Biederman　has　proposed　that　all　objects　can　be　assembled　from　
a　set　of　geometrical　ions；　or　geons。　From　a　set　of　36　geons；　Biederman　
believes　that　perception　can　make　a　strong　guess　at　the　nature　of　an　
object。　
C。　The　Influence　of　Contexts　and　Expectations　
1。　Expectations　can　influence　hypotheses　about　what　is　out　there　in　the　
world　and　can　influence　what　is　actually　perceived　
2。　It　takes　longer　to　recognize　an　object　when　it　is　seen　in　the　wrong　
context；　not　in　a　familiar　place　
3。　Object　identification　is　a　constructive；　interpretive　process　
4。　Set　is　a　temporary　readiness　to　perceive　or　react　to　a　stimulus　in　a　
particular　way。　There　are　three　types　of　sets：　motor；　mental；　and　
perceptual。　
a）　A　motor　set　is　a　readiness　to　make　a　quick；　prepared　response　

b）　A　mental　set　is　a　readiness　to　deal　with　a　situation；　such　as　a　
problem…solving　task　or　game；　in　a　way　determined　by　learned　
rules；　instructions；　expectations；　or　habitual　tendencies。　
Mental　sets　can　actually　prevent　problem…solving　when　old　
rules　do　not　fit　new　situations。　

c）　A　perceptual　set　is　a　readiness　to　detect　a　particular　stimulus　
in　a　given　context　

D。　Creatively　Playful　Perception　
1。　Perceptual　creativity　involves　experiencing　the　world　in　ways　that　are　
imaginative；　personally　enriching；　and　fun　
E。　Final　Lessons　
1。　A　perceptual　experience　in　response　to　a　stimulus　event　is　determined　
not　only　by　the　stimulus　but　also　by　the　person　experiencing　it。　In　
addition　to　sensation；　final　perception　depends　on　past　experience；　
expectations；　wants；　goals；　values；　and　imagination。　
2。　A　proper　balance　of　top…down　and　bottom…up　processing　achieves　the　
basic　goal　of　perception：　to　experience　what　is　out　there　in　a　way　that　
maximally　serves　your　needs　as　a　biological　and　social　being；　moving　
about　and　adapting　to　your　physical　and　social　environment。　
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CHAPTER　5：　PERCEPTION　

DISCUSSION　QUESTIONS　

1。　Why　are　there　separate　chapters　on　sensation　and　perception？　What　are　the　differences　
between　the　two？　
2。　Which　is　more　susceptible　to　cultural　or　contextual　influence；　sensation　or　perception？　
Why？　
3。　How　are　individuals　able　to　tell　when　their　perceptions　have　been　influenced　by　cultural　or　
contextual　factors？　Is　there　a　way　to　eliminate　these　biases　from　perception？　These　factors　
probably　always　influence　perception；　but　knowing　that　they　do　gives　the　perceiver　
knowledge　that　may　help　minimize　its　negative　impact。　
4。　Are　the　differences　in　perception　among　humans　likely　to　be　larger　or　smaller　than　the　
differences　in　perception　among　ants？　Assuming　that　human　cultures　are　more　diverse　
than　ant　cultures；　the　differences　in　perception　should　be　greater　for　humans。　Larger　
cultural　differences　would　produce　larger　variations　in　perception。　
5。　You　might　ask　students　if　they　believe　that　advertisers　put　hidden　messages　in　their　
advertisements。　Follow　up　by　asking　if　they　believe　those　messages　work。　You　can　use　this　
to　lead　into　a　discussion　of　subliminal　perception　and　its　supposed　effects。　Stories　of　
subliminal　visual　messages　go　back　to　claims　of　their　inclusion　in　movies　in　the　1950s。　
Subliminal　verbal　messages　have　been　discussed　at　least　since　the　controversy　about　the　
Beatles　supposedly　putting　hidden　messages　in　their　albums　in　the　late　1960s。　However；　
the　evidence　that　these　messages　have　any　real　effect　on　behavior　is　currently　lacking。　
Stories　about　subliminal　messages　continue　to　regularly　appear　in　the　media；　and　it　is　
surprising　how　many　people　believe　that　the　messages　work。　
6。　As　an　example　of　motion　parallax；　you　might　ask　students　if　they　have　ever　traveled　with　
young　children　on　a　clear　night　with　the　moon　near　the　horizon　to　one　side　of　the　road　on　
which　you　are　traveling。　Whereas　the　trees；　houses；　and　hills　seem　to　move　steadily　by；　the　
moon　appears　to　be　traveling　along　with　you。　Many　times　young　children　will　exclaim　that　
the　“moon　is　following　us。”　There　have　even　been　UFO　reports　generated　by　this　
phenomenon　on　cloudy　nights　when　adults　have　mistaken　the　moonlight　for　a　flying　object　
darting　in　and　out　of　the　clouds　and　following　them　along　the　horizon。　
7。　To　illustrate　the　fact　that　the　brain　interprets　messages　from　the　skin’s　hot　and　cold　
receptors　relative　to　previous　and　surrounding　stimuli；　set　up　three　small　basins　in　the　
front　of　the　class。　Fill　one　with　hot　water　（but　not　so　hot　that　it　will　burn　someone’s　skin）；　
one　with　cold　water；　and　one　with　luke…warm　water。　Have　students　put　one　hand　in　the　
basin　of　hot　water　and　the　other　hand　in　the　basin　of　cold　water。　Then　have　them　place　
both　hands　in　the　basin　of　warm　water。　They　should　notice　that　in　the　warm　water；　one　
hand　（the　one　that　was　in　the　cold　water）　will　sense　it　as　being　hot；　while　the　other　hand　
（the　one　that　was　in　the　hot　water）　will　sense　it　as　being　cold。　
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PSYCHOLOGY　AND　LIFE　

SUPPLEMENTAL　LECTURE　MATERIAL　

Eyes　and　Camera　Lens　

For　many　years；　it　was　believed　that　the　eye　worked　like　a　camera；　and　there　are　some　similarities。　
For　instance；　both　the　pupil　of　the　eye　and　the　aperture　of　a　camera　contract　and　expand　in　
response　to　a　respective　increase　or　decrease　in　the　amount　of　light　entering　the　apparatus。　
Nevertheless；　in　paring　the　human　eye　to　a　camera；　some　of　the　differences　between　these　two　
are　striking。　

Perhaps　the　strangest　difference　between　the　human　eye　and　a　camera　lens　is　the　position　of　the　
retina　and　the　analogous　film。　For　a　camera　to　be　like　the　human　eye；　we　would　have　to　load　our　
film　into　the　camera　backward。　That　is；　the　photoreceptors　actually　pick　the　light　up　off　the　back　of　
the　surface　of　the　eyeball。　A　camera　must　be　held　relatively　still　to　capture　a　clear　image；　but　when　
the　eyeball　is　held　still；　the　picture　disappears。　Both　the　camera　and　the　eye　have　a　lens　that　focuses　
an　image　on　a　surface；　but　the　two　have　different　methods　of　focusing。　The　lens　in　a　camera　moves　
closer　to　or　farther　from　the　film　in　order　to　focus　the　image　on　the　film；　the　lens　in　the　eye　changes　
shape　to　focus　the　image　on　the　retina。　This　process　is　called　acmodation。　

An　upside…down　mirror　image　is　focused　on　both　the　film　and　the　retina；　however；　the　film　and　the　
retina　differ　in　that　the　film　records　the　image　exactly　as　it　is　projected。　The　photoreceptors　in　the　
retina　receive　information　from　visual　stimuli；　those　stimuli　are　analyzed　and　reconstructed　as　they　
move　through　the　visual　system　from　the　retina　to　the　cortex。　What　we　perceive　is　a　picture　that　is　
not　identical　to　the　item　we　are　looking　at。　Photographs　in　which　people　have　their　feet　extended　
closer　to　the　camera　in　front　of　them　are　ical　because　we　take　relative　distances　into　account　and　
perceive　the　feet　as　being　a　constant　size。　

Everyday　Examples　of　Gestalt　Principles　

Bring　in　everyday　examples　of　the　Gestalt　principles　of　perception　from　magazines　or　artworks。　

Transparencies　of　the　examples　can　be　made　on　a　copy　machine；　and　then　used　on　overhead　
projectors。　For　example；　in　Escher’s　Mosaic　II；　one　sees　a　group　of　black　creatures　on　either　a　white　
background　or　a　group　of　white　creatures　on　a　black　background。　H。　A。　Broos　explains　how　

Escher’s　prints　have　been　used　in　geology；　chemistry；　and　psychology　in　The　World　of　M。　C。　Escher。　
This　book　also　contains　a　chronological　survey　of　Escher’s　work　and　includes　a　number　of　useful　
examples；　such　as　illustrations　of　figure　and　ground　in　the　woodcuts　“Sky　and　Water　I”　and　“Sky　
and　Water　II。”　

A　Brief　History　of　Gestalt　Psychology　

The　Gestalt　movement　in　psychology　was　established　in　Germany　in　the　early　1900s；　and　was　
based　on　the　Gestaltist’s　opposition　to　the　structuralist　movement。　In　essence；　the　structuralist　
movement　proposed　that　all　phenomena　could　be　broken　down　into　their　most　primitive　perceptual　
elements。　The　Gestaltists　took　exception　to　that　philosophy；　arguing　that　psychological　phenomena　
could　be　understood　only　if　they　were　studied　as　organized；　structured　“wholes；”　thus　maintaining　
the　“unitary　essence”　of　the　phenomena。　

The　Gestaltists　extended　this　philosophy　to　learning；　in　viewing　it　as　a　restructuring　or　
reorganization　of　an　entire　situation；　and　a　process　that　often　included　insight　as　a　critical　aspect　of　
that　process。　Brain　physiology　was　perceived　in　the　same　context；　in　that　Gestaltists　saw　the　brain　
as　isomorphic；　as　having　a　relationship　between　the　excitatory　fields　in　the　cortex　and　the　
conscious　experience　of　the　individual。　

Gestalt　psychology；　as　a　distinct　discipline；　is　rarely　found　today；　although　many　of　the　insights