[VERSION 2] COMPLETE Perception and Behavior Notes: Part 2 -- 4.0ed this course!

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Psychological & Brain Sciences
CAS PS 222
All Professors

Midterm  II  Study  Guide     Chapter  6-­‐  Visual  Attention     • Attention-­‐  the  brain’s  most  powerful  tool  to  allocate  mental  resources  to  sensory  and   perceptual  information  in  the  environment.   Attention  is:   o Selective   o Shiftable     o Divisible     • Divided  Attention-­‐  the  limited  ability  of  paying  attention  to  more  than  one  thing  at  a  time.   Example:  driving  and  texting -­‐  don’t  mix.     • Selective  Attention-­‐  focusing  on  specific  objects  and  filtering  out  others.     o Visual  system  constructed  this  way.   § Too  much  information  for  the  retina  to  handle.     § Fovea  helps  achieve  selection.     • Eye  movements  take  in  different  parts  of  a  scene   o Saccades-­‐  small,  rapid  eye  movements.   o Fixations-­‐  pauses  indicating  where  the  person  pays  attention.   o ~3  fixations/second     • Factors  determining  location  of  fixations   o Stimulus  Salience-­‐  areas  of  a  scene  that  attract  attention  because  of  shape,  color,   size  or  orientation.  Saliency  maps  show  these  properties  are  fixed  on.     o Scene  Schema-­‐  prior  knowledge  about  what  is  found  in  typical  scenes.     § Influence  on  task:   • Stimulus  saliency  overridden   • Saccades  and  fixations  linked  to  action .   o Effects  of  Past  Experience -­‐  example-­‐  detecting  stop  signs  at  intersections  and   stopping  there.     • Perception  without  focused  attention -­‐  experiment  by  Reddy  et  al.     o Central  task-­‐  letters  flashed  in  center  of  the  screen  are  the  same.     § 80-­‐90%  performance   o Peripheral  task-­‐  faces  flashed  to  the  side  of  the  screen  are  male  or  female.     o Dual  task-­‐  same  as  peripheral  task  but  determine  color  of  disk.     § Faces-­‐  90%  performance   § Discs-­‐  54%  performance     o Results   § Gender  determined  without  focused  attention,  while  color  of  disc  couldn’t.     o Conclusion:  faces  have  meaning  and  are  perceived  as  whole  objects.   • Inattentional  blindness-­‐  stimulus  not  perceived  even  when  the  person  directly  looks  at  it.     o Passing  around  ball  experiment -­‐  46%  of  people  didn’t  see  gorilla.   • Change  blindness-­‐  a  change  in  a  stimulus  not  perceived  after  interruptions  in  visual  field.   o Scene  presentedà  blank  screenà  slightly  changed  scene  presented   o Subjects  noticed  changes  more  quickly  when  pointed  out  to  them.     o Real  objects  in  the  environment  chang e,  which  is  why  we  don’t  notice  them  as   much.     • Binding-­‐  process  by  which  features  are  combined  to  create  perception  of  coherent  objects.     o Example:  a  rolling  ball  activates  a  number  of  different  areas  of  the  cortex  that  deal   with  say  form,  color,  depth,  motion  and  location.  These  signals  combine  to  form  a   unified  percept.       Feature  Integration  Theory     Preattentive  Stage-­‐  features  of  objects  separated.     Focused  Attention  Stage -­‐  features  combined  into  coherent  perception.   Attention  is  glue  for  what  and  where  streams.     • Illusory  Conjunctions-­‐  features  associated  with  one  object  become  incorrectly  associated   with  another.     o Balint’s  Syndrome-­‐  damage  to  parietal  lobe  causes  inability  to  focus  attention  on   individual  objects  and  results  in  incorrect  combinations  or  features.     • Visual  Search-­‐  conjunction  search-­‐  find  target  with  two  or  more  features.     o Parietal  lobeà  where  stream   o Parietal  lobe  damage-­‐  no  conjunction  search   Physiological  Approach  to  Binding   • Synchrony  Hypothesis-­‐  neurons  firing  to  the  same  object  (or  different  qualities  of  the  object)   synchronize  with  each  other.     o Same  firing  pattern   o Attention  may  help  synchronize  neural  firing.     Physiology  of  Attention   • Colby  et  al.  experiment   o Monkey  fixates  on  dot  while  peripheral  light  flashed  on  the  right.     § Fixation  only  condition:  keep  eyes  fixated  and  release  lever  when  dot   dimmed.     § Fixation  and  attention  condition:  keep  eyes  fixated  and  release  lever  when   peripheral  light  dimmed.   § Recordings  from  neuron  in  parietal  lobe  that  responded  to  peripheral  light   made.     o Results   § Neuron  fired  well  when  monkey  attended  to  peripheral  light.     § Neuron  fired  poorly  when  monkey  wasn’t  attending  to  peripheral  light.     § Response  was  due  to  attention.     Chapter  7-­‐  Taking  Action     Ecological  Approach  to  Perception   • Look  for  information  in  the  environment  that  provides  information  for  perception.     • Stresses  relationship  between:   o Organism  and  environment   o Perception  and  action   • Information-­‐  optic  array-­‐  structure  created  by  surfaces,  textures  and  contours  in  the   environment.     o Optic  flow-­‐  appearance  of  object  as  the  observer  moves  past  them.   Two   characteristics   § Flow  is  more  rapid  near  the  moving  observer.   • Gradient  of  flow-­‐  difference  in  speed  of  flow  dependent  on  distance   from  observer.     § No  flow  at  the  destination  toward  which  the  observer  is  moving.   • Focus  of  Expansion-­‐  point  in  distance  where  there  is  no  flow.     • Invariant  Information-­‐  properties  that  remain  constant  while   observer  is  moving.     • Self-­‐produced  information-­‐  flow  is  created  by  the  movement  of  the  observer.     o Skilled  actions  establish  connection  between  sensory  and  motor  systems.   o Example:  gymnasts  can’t  perform  with  eyes  closed.             • Vision  very  important  in  balance   o 13-­‐16  month  old  children  put  in  “swinging  room”  where  floor  stationary  but  walls   and  ceilings  swung.     o Children  swayed  back  and  forth.     o Adults  showed  the  same  result.   o Result:  vision  has  a  powerful  effect  on  bala nce  and  overrides  other  sen ses.   Navigating  Through  the  Environment   • Land  and  Lee  Study   o Method:  car  fitted  with  measurement  tools  for  angle  of  steering  wheel,  speed  and   gaze  of  driver.     o Experiment:  when  driving  straight,  driver  looks  ahead  and  not  at  focus  of  expansion.     § When  turning  a  curve,  driver  looks  at  tangent  point  at  the      of  the  road.   • Suggests  noting  position  of  car  in  relation  to   centerline  or  side  of  the   road.     Physiology  of  Navigation   • Optic  Flow  Neurons-­‐  neurons  in  the  medial  superior  temporal  area  (Mrespond  to   flow  patterns.     • Experiment-­‐  monkeys  trained  to  respond  to  direction  of  flow  of  dots  on  screen  (left,  right  or   straight).   o As  task  done  MST  stimulated  that  respond  to  specific  direction  of  flow  patterns.     o Judgments  shifted  in  direction  of  stimulated  neuron.     o Result-­‐  stimulation  increased  judgment  of  movement  in  a  direction.     • Experiment-­‐  London  cab  drivers  given  destination  on  map  and  midway  the  destination  was   changed.  They  also  heard  a  statement  unrelated   to  their  destination.   o  fMRI  monitored  brain  activity.   o Results  showed  link  between  brain  activation  and  specific  navigation  tasks.     § Activation  of  visual  cortex  and  PPA  for  inspecting  buildings.     § Activation  of  hippocampus  and  PPA  for  planning  routes.     Acting  on  Objects   • Affordance  of  object-­‐  information  indicating  what  an  object  is  used  for.     o Indicate  potential  for  action  as  part  of  our  perception.   o Certain  types  of  brain  damage -­‐  cannot  name  but  can  still  pick  up  object  and  use  it.     o Tea-­‐cup  experiment  of  not  recognizing  it  unless  it  had  a  handle.     • Physiology  of  Reaching  and  Grasping   o Experiment:  neurons  in  parietal  lobe  silent  when  monkey  does  not  act,  fire  up  when   monkey  reaches  button  to  receive  food.     § Only  happened  when  animal  was  reaching  to  achieve  a  goal.     § Goal-­‐directed  neurons  identified  in  Parietal  Reach  Region.     Observing  Other  People’s  Actions   • Mirror  neurons-­‐  neurons  in  premotor  cortex  that  respond  when  subject  observes  someone   else  grasp  an  object.     o Response  to  the  observed  action  mirrors  response  of  actually  grasping.     • Possible  functions   o Help  understand  other  animals’  actions  and  have  proper  reaction.   o Help  imitate  observed  action.     o Link  sensory  perceptions  and  motor  actions.     • Audiovisual  mirror  neuro ns-­‐  respond  to  action  and  accompanying  sound.                   • Experiment-­‐   mirror   neurons  and   experience   o Three  groups   § Professionally  trained  ballet  dancers   § Professionally  trained  capoeira  dancers   § Control  group  of  non-­‐dancers   o Two
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