Percep&on  and  Comprehension  

MAR  3503    

January  19,  2012  

How  do  we  take  in  informa&on?  

Exposure  

External  S&muli  

Sights  

Sounds  

Smells  

Tastes  

Touch/Movement   Heat,  pressure,  &  motor  receptors  

Tongue  

Nose  

Ears  

Eyes  

Sensory  Receptors  

ANen&on  

Percep&on  

Comprehension  

Behavior  

Psychophysics:  Sensa&on  and  percep&on  

•  Sensa&on:  –  The  immediate  response  of  our  sensory  receptors  to  basic  s&muli  such  as  light,  color,  sound,  scent,  touch,  taste…  

–  Sensa&on  is  physical    •  Percep&on  

–  The  process  by  which  sensa&ons  are  selected  and  organized  

–  Percep&on  is  what  we  add  to  raw  sensa&ons  so  that  we  can  be  interpreted  

–  Percep&on  is  psychological  •  It’s  ac&ve  •  It’s  rela&ve  

What  do  we  perceive?  •  Absolute  threshold  

–  The  lowest  intensity  of  a  s&mulus  that  can  be  perceived  via  a  sensory  channel  

–  Basic  method  •  Ascending  method  of  limits  

–  Start  with  a  low  value  of  a  s&mulus  (Ex.  Sound)  –  Increase  un&l  the  person  say  “I  hear  something”  

•  Descending  method  of  limits  –  Start  with  a  very  high  value  of  s&mulus  –  Decrease  un&l  the  person  says  “I  don’t  hear  anything”  

•  Absolute  threshold  can  be  quite  low  (indica&ng  sensi&vity)  –  But  differs  by  individual  

Subliminal  percep&on  

•  The  ac&va&on  of  sensory  receptors  by  s&muli  presented  below  the  perceptual  threshold  

•  We’re  aNending  to  a  s&mulus,  and  something  flashes  so  quickly  (e.g.,  30  msec)  that  we  can’t  consciously  perceive  it  

•  Can  this  kind  of  percep&on  influence  our  behavior?  

Subliminal  percep&on  

•  In  1957,  James  Vicary  repeatedly  flashed  a  frame-­‐long  image  that  read  either  “Drink  Coke”  or  “Eat  popcorn”  during  a  movie  

•  He  claimed  that  popcorn  sales  increased  58%  and  soda  sales  increased  18%  

•  He  later  admiNed  that  “the  amount  of  data  he  had  collected  was  so  small  as  to  be  useless,”  but  s&ll…  

•  His  claim  opened  the  door  to  Cold  War  fears  of  subliminal  propaganda    

Subliminal  percep&on  works  •  …a  liNle  

– Mere  exposure  showed  us  that  subliminal  percep&on  of  a  s&mulus  can  lead  to  increased  liking  for  the  s&mulus  

–  Subliminal  presenta&on  of  a  word  will  lead  you  to  recognize  that  word  more  quickly  later  on  

–  Subliminal  exposure  to  adjec&ves  can  influence  judgments  of  later  targets  

•  But  it’s  hard  to  make  it  subliminal  for  everyone  – May  make  the  s&mulus  too  weak  or  too  strong  –  Need  to  get  people  to  aNend  to  the  s&mulus  loca&on  –  Need  to  make  sure  the  presenta&on  is  just  at  the  right  distance  

Subliminal  persuasion  

•  Par&cipants  were  thirsty  when  they  came  into  the  lab  •  They  then  were  exposed  to  subliminal  thirst  primes  or  neutral  primes,  to  make  sure  thirst  was  on  their  mind  

•  They  then  read  about  two  sports  drinks:  Power  Pro  (the  best  electrolyte  balancing  drink)  and  Super  Quencher  (the  more  thirst  quenching  drink)  

•  They  then  rated  the  two  products  as  to  how  much  they  felt  posi&vely  about  them,  and  took  as  many  coupons  as  they  wanted  for  either/both  drinks  

Strahan,  Spencer,  &  Zanna,  2002  

Subliminal  persuasion  

Thirst-­‐prime  par&cipants  also  chose  more  Super  Quencher  coupons  (M  =  5.31)  than  neutral  prime  par&cipants  (M  =  4.27)  

Strahan,  Spencer,  &  Zanna,  2002  

Subliminal  persuasion  •  Par&cipants  were  brought  into  the  lab  and  given  a  salty  treat  that  made  them  thirsty,  or  given  no  treat  

•  Then  they  were  subliminally  primed  with  the  words  “Lipton  Ice,”  which  is  a  brand  of  iced  tea  

•  Aker  the  priming  they  were  given  the  op&on  of  two  drinks,  Lipton  Ice  or  a  boNled  water  –  They  picked  which  one  they  would  rather  have  at  that  moment  

–  They  rated  their  inten&ons  to  drink  each  op&on  in  the  future  

Karremans,  Stroebe,  &  Claus,  2006  

Subliminal  persuasion  

Karremans,  Stroebe,  &  Claus,  2006  

Organizing  principles  of  percep&on  

•  Percep&on  is  ac&ve!  

•  Gestalt  psychology:  – When  we  see  an  item,  we  evaluate  it  as  a  “whole  thing,”  not  as  a  collec&on  of  its  &ny  parts  

– Percep&on  of  the  whole  is  different  from  (and  more  important  than)  percep&on  of  the  parts  

Closure  

Proximity  

Similarity  

Figure-­‐Ground  

Con&nua&on  

Illusions  

How  do  we  perceive?  

•  One  commonly-­‐held  view  –  Realism:  We  see  the  world  as  it  is.  We  simply  register  sensory  inputs  and  report  them  back.  

•  Another  (more  accurate)  view:  – Naïve  realism:  We  believe  we  see  the  world  as  it  is.  Percep&on  is  an  ac&ve,  construc&ve  process.  We  use  prior  informa&on,  as  well  as  current  expecta&ons,  goals  and  desires  when  interpre&ng  incoming  informa&on.  

–  The  Gestalt  principles  give  one  illustra&on  of  the  ac&ve  nature  of  percep&on  

 

We  don’t  always  perceive  things  as  they  are  

•  Is  seeing  believing?  Or  is  believing  seeing?  

•  Belief  about  a  product  can  influence  percep&on  of  the  product  – New  Coke,  same  old  7-­‐up  – Coors  “banquet  beer”  versus  “original  drak”  – “Chocolate”  pudding  flavors  – Light-­‐colored  appliances  

Our  bodies,  our  worlds  

•  Our  physical  self  can  affect  how  we  see  the  outside  world  

•  People  mises&mate  the  slope  of  hills  and  distances  all  the  &me  

•  But  when  we  are  low  on  resources—encumbered  by  a  heavy  backpack,  &red,  older—we  see  the  same  slopes  and  distances  as  steeper  or  longer  

•  When  we  have  added  resources,  even  social  ones,  these  same  obstacles  appear  less  difficult  to  overcome  

ProffiN,  2006  

Swinging  at  aspirins  

•  Sokball  players  were  asked  to  es&mate  the  size  of  a  sokball  by  choosing  one  of  8  circles  

•  They  were  also  asked  to  report  their  stats  •  The  beNer  players  chose  a  larger  circle  to  represent  the  ball  

WiN  &  ProffiN,  2005  

We  see  what  we  expect  to  see  

•  We  perceive  and  interpret  ambiguous  s&muli  in  line  with  what  we  expect  them  to  be  

 •  Heart  rate  measured  when  they  were  approached  by  an  aNrac&ve  female  assistant  

•  Heart  rate  increased  not  for  those  who  drank  only  tonic  (Groups  3  &  4),  but  instead  for  those  who  thought  they  only  drank  tonic  

Told  was  vodka  &  tonic   Told  was  only  tonic  

Drank  vodka  &  tonic   Group  1   Group  2  

Drank  only  tonic   Group  3   Group  4  

Seeing  what  we  (don’t)  want  to  see  

Comprehension  

•  …Is  the  process  of  understanding  and  giving  meaning  to  that  which  we  have  just  perceived  

•  …Is  intertwined  with  percep&on:  – We  just  saw  how  percep&on  is  expectancy-­‐based  –  This  can  make  it  difficult  to  say  where  percep&on  ends  and  comprehension  begins  

•  A  key  component  of  comprehension  is  categoriza&on  – …which  is  the  process  of  labeling  or  iden&fying  a  perceived  object  

Consequences  of  categoriza&on  

•  Categoriza&on  evokes  the  schema  of  the  category  •  A  schema  is  a  set  of  associa&ons  linked  to  a  concept  or  category  –  Ex.  Luxury  car  

•  Associa&ons  can  include:  •  ANributes  •  Benefits  •  Drawbacks  •  Users  •  Use  situa&ons  

–  Associa&ons  can  be:  •  Unique/not  unique  •  Favorable/not  favorable  

Consequences  of  categoriza&on  

•  We  then  apply  the  evoked  category  schema  to  the  new  target  –  “If  this  is  a  luxury  car,  then  it  must  be…”  

•  Because  of  this  categoriza&on  and  schema-­‐applica&on,  we  can  then  more  easily…  – Make  inferences  about  the  new  target  –  Evaluate  the  new  target  –  Include  or  exclude  the  new  target  in  our  considera&on  set  

– Decide  whether  we  are  sa&sfied/unsa&sfied  with  the  new  target  

Consequences  of  categoriza&on  

•  The  applica&on  of  schemas  predicts  that  certain  things  will  happen  when  categoriza&on  goes  wrong  

•  We  may  make  incorrect  inferences  about  what  the  target  is,  and  what  it  should  do  –  Sunlight  Dishwashing  Detergent  – Maalox  Whip  Antacid  

•  So,  it’s  important  that  people  categorize  your  product  correctly  so  that  the  right  schema  is  evoked  

Comprehension:  Inferences  

•  To  be  successful  at  communica&on,  we  need  to  make  inferences  – “My  pen  stopped  working”  – “It’s  hot  in  here”  – “Do  you  know  how  to  get  to  the  Reitz  Union?”  

•  Inferences  are  usually  beneficial,  but  our  tendency  to  make  inferences  can  lead  us  astray  

Misinterpreta&ons  

•  “Technically  true”  statements  about  products  may  encourage  misinterpreta&ons  and  incorrect  inferences  

•  “Lysol  kills  flu  and  other  germs  on  surfaces”  

•  “Ocean  Spray  cranberry  juice  has  more  food  energy  than  orange  or  tomato  juice”  

Misinterpreta&on  

•  Some  types  of  true  statements  that  lead  to  false  inference  – Comparison  omission  •  Our  gasoline  gives  you  beNer  mileage  

–  BeNer  mileage  than  what?  

– Piecemeal  informa&on  •  Our  car  has  more  headroom  than  a  Mercedes,  more  legroom  than  a  Cadillac,  more  trunk  space  than  a  BMW  

– Affirming  the  consequent  • Women  who  look  younger  use  Oil  of  Olay  

–  Does  not  answer  the  ques&on,  “If  I  use  Oil  of  Olay,  will  I  look  younger?”  

•  Essen&ally,  it  is  this  argument:  –  If  P,  then  Q.  – Q  is  true.  – Therefore,  P  is,  too.  

•  The  problem  is  that  P  isn’t  the  only  possible  cause  of  Q.  –  If  Bill  Gates  owns  Fort  Knox,  then  Bill  Gates  is  rich.  – Bill  Gates  is  rich.  – Therefore,  Bill  Gates  owns  Fort  Knox.  

Affirming  the  consequent  

Summary  •  There  are  methods  for  measuring  what  will  and  will  not  be  

perceived  •  Subliminal  may  have  small,  but  not  large,  effects  on  

behavior  •  Percep&on  is  an  ac&ve  process  

–  We  organize  what  we  see  into  meaningful  s&muli  –  What  we  perceive  is  influenced  by  prior  expecta&ons,  beliefs,  and  desires,  and  oken  confirms  those  beliefs  

•  Comprehension  involves  giving  meaning  to  what  we  perceive  –  We  need  to  categorize  new  s&muli  –  We  need  to  make  inferences—which  can  lead  us  astray  

–  Next  &me:  How  does  memory  work?