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Lecture

Ch. 4 - Attention (1).pdf

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School
McMaster University
Department
Psychology
Course
PSYCH 2H03
Professor
Judith Shedden
Semester
Fall

Description
PNB  2XA3   Chapter  4:  Attention     Inattentional  Blindness   • Do  you  sometimes  “look”  but  no t  “see”?   • Simons  &  Levin,  1998   o Experimenter  1  stopped  a  pedestrian  on  the  quad  (Cornell),  to  ask  for  directions.  Two  people  carrying  a   door  walked  through  the  conversation.  Experimenter  1  changed  places  with  one  of  the  door  carriers   (Experimenter  2),  and  carried  on  the  conversation.  When  told,  “this  is  a  Psychology  experiment  about  the   things  people  pay  attention  to  in  the  real  world.  Did  you  notice  anything  unusual  at  all  wh en  that  door   passed  by  a  minute  ago?”  Only  ½  the  people  said  they  noticed  anything  at  all.     Change  Blindness   • We  do  not  store  very  detailed  visual  representations  of  much  of  what  we  perceive.   • Attention  is  critical:  to  see  we  must  attend.  But  sometimes  atten ding/searching  is  difficult!     Processing  Capacity  &  Selective  Attention   • Bottleneck  metaphor   o Is  there  a  bottleneck?  Where  is  the  bottleneck?  What  kind  of  info  gets  through  the  bottleneck?  How  do  we   control  it?   • Broadbent  (1985)  –  Early  Selection   o Bottleneck  occurs  at  or  prior  to  the  stage  of  perceptual  analysis   o Filter  early  sensory  info  based  on  physical  characteristics   o i.e.  A  switch  –  on  or  off,  things  get  in  or  don’t  get  in   • Treisman  (1964)  –  Attenuation  Theory   o Still  filtering  based  on  physical  properties,  b ut  the  unattended  message  is  only  weakened,  not  blocked.   o i.e.  a  “leaky”  filter   • Beutch  &  Deutch  (1963)  –  Late  Filter   o All  sensory/perceptual  info  goes  through  to  analysis,  but  the  LATE  filter  blocks  responding  to  the  wrong   one,  which  is  then  forgotten.     Sterling  (1960)   • Task  1:  full  report  on  everything  seen   • Task  2:  partial  report  on  what  was  seen   • The  time  it  takes  to  respond  leads  to  info  fading  away   • Used  cues  –  high,  middle,  low  tone  –  that  came  on  after  the  visual  display  already  came  on  and  disappeared.   Therefore,  you  either  report  top,  middle,  or  bottom  row.     Dichotic  Listening  Task   • When  shadowing  the  attended  channel,  people  often  can’t  even  tell  whether  the  unattended  channel  was  nonsense   or  not.  Can’t  remember  the  unattended  info  at  all.   • Early  selection  isn’t  quite  right   o Does  ANY  info  from  the  ignored  message  get  through?   § YES!  You  aren’t  deaf  to  the  unattended  channel.  You  can  tell:  h uman  or  not,  male  or  female  etc.   You  can  report  low  level  perceptual  info  if  you  are  asked  about  it.                           Priming  &  Attention   • Why  can  you  hear  your  name  even  when  it  was  in  an  unattended  channel?  You  name  is  always  primed  for  you,   activation  baseline  is  high.  Easy  for  your  “name”  detectors  to  fire.   • Why  is  it  easier  to  shadow  regular,  predictable  messages?  If  y ou  know  what  to  expect,  easy  to  prime  the  appropriate   detectors.   • Using  mental  chronometry  to  measure:   Repetition  Priming  and  Expectation  Priming   o Task:  Are  the  2  letter  the  same  or  different?   AA  =  SAME!,  AB  =  DIFFERENT!         o Low  validity  condition   § Letter  cue:  low  20%  probability  that  the  test  stimulus  would  contain  the  same  letter,  leading  to  no   basis  for  expectation.   o High  validity  condition   o Letter  cue:  high  80%  probability  that  the  test  stimulus  would  contain  the  same  letter  (correct   expectation.   • What  do  the  costs  and  benefits  mean?   o Repetition  priming  –  warming  up  one  detector  doesn’t  have  any  effect  on  another  detector.  Priming  helps   you,  misleading  doesn’t  hurt  any  worse  than  neutral.   o Expectation  based  priming  –  expecting  one  thing  hurts  you  in  perceiving  another  (this  is  you  attention   budget).  Attention  deals  with  preparing  for  upcoming  info,  and  is  a  limited  capacity  system.   o Mental  tasks  have  a  “cost”   –  can  do  multiple  things  at  once  if  it  is  within  your  ment al  budget.  If  you  go  over   your  budget,  performance  suffers.     Space-­‐based  Attention/Object-­‐based  Attention   • Space-­‐based:  We  can  prime  a  location  in  space  in  a  similar  manner  to  priming  a  detector.       • Object-­‐based:     Unilateral  Neglect  Syndrome   • Attention  deficit  usually  due  to  stroke.  It  is  space-­‐based  (hemisphere).   • Damage  to  right  hemisphere  leads  to  neglect  in  left  hemisphere  but  patients  won’t  notice.   o Inability  to  direct  attention  to  left  side  (bumping  into  things  on  left  side…)   • Damage  to  left  hemispher e  is  not  as  severe  (can  still  pay  attention  to  both  visual  fields).                     What  happens  with  the  ignored  distractors?   • Filtering  is  tune  to  specific  distractors   o Practice  is  specific  to  the  context  and  the  specific  distractors   o Actively  inhibiting  or  blocking  distracting  info??   • Negative  Priming  (so  called)   o If  you  ignore  an  item  on  one  trial,  you  are  subsequently  slower  if  you  have  to  respond  to  that  same  item  on   the  next  trial.   à  Ignore  E  on  1  trial,  ignore  P  on  2  trial.  Therefore  harder  to  see  E  on  2  trial.     Priming  Metaphor   • We  promote/enhance/select  for  the  inputs  that  are  important.  We  do  NOT  do  this  for  distractors .   • Think  of  this  term  of  priming  the  detectors .  Selected  input  will  be  primed  while  distractors  will  not  be   primed….unless  they  already  ARE  primed  (i.e.  salient).       Dichotic  Listening   • Subjects  wears  headphones,  hears  input  in  left  ear  and  different  input  in  right  ear.  Told  to  listen  to  one  input   –   attended  channel  –  and  ignore  other  input  –  unattended  channel.   • Shadowing:  Used  to  ensure  subjects  were  paying  attention.  Subjects  were  required  to  repeat  what  was  said  in   attended  channel.  Shadowing  performance  was  close  to  perfect,  but  heard  very  little  from  unattended  channel.     Cocktail  Party  Effect   • Subjects  asked  to  shadow  one  passage  while  ignoring  a  second  passage.  Embedded  within  unattended  channel  was   a  series  of  names,  about  1/3  of  subjects  heard  their  own  name  even  though  they  heard  nothing  else  from   unattended  channel.     Inattentional  Blindness   • Subjects  told  they  would  see  a  large  +  on  screen  followed  by  a  mask.  If  the  horizontal  bar  in  +  was  longer  than  the   vertical,  the  subjects  were  to  press  one  button;  if  vertical  bar  was  longer,  they  were  to  press  a  different  button.   Subjects  were  not  allowed  to  look  directly  at  t he  +.  Instead,  they  fixated  a  mark  in  the  center  of  the  screen   –  fixation   target  –  and  the  +  was  shown  off  to  one  side.   o Trials  1&2  =  relatively  easy.  Trial  3  =  78%  correct.   o Trial  4  =  Fixation  target  disappeared  and  replaced  by  a  triangle,  rectangle,  or  cro ss.  89%  of  subjects   reported  that  there  was  no  change.  They  failed  to
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