WEEK 4- ACHIEVING OBJECT CONSTANCY FOR PLANE ROTATION

Question 1

What is plane rotation?

Answer 1

it means that the objects rotation is rotating in the picture plane. it is the plane perpendicular to the direction you are looking

Question 2

what is the standard view you would see in the world?

Answer 2

0 degrees

Question 3

what are the proposals for how is object constancy achieved for plane rotation?

Answer 3

1. using mental rotation transformations
2. assuming no cost for plane rotation unless people double-check (so view-invariant features unless use mental rotation)
3. assuming no cost for plane rotation unless recognition is at subordinate level
4. store multiple views for each familiar obejct; only transform stimuli if they are presented at an unfamiliar view - GOING TO LOOK AT ALL FOUR OF THESE OPTIONS

Question 4

Who says we do a mental rotation within our brains?

Answer 4

Cooper and Shepard

Question 5

what did Cooper and Shepard use to suggest we do a mental rotation (ie the first proposal)

Answer 5

• cubes attached at different angles
• people had to decide whether they were the same object or mirror images.
• they gave people lots of these pairs and asked people to decide as quickly as possible

Question 6

what did Cooper and Shepard find about the time to decide whether two figures were identical ? (except for a plane rotation and mirror images)

Answer 6

• they found that the time to decide whether two figures were the same increases linearly as the angle between the two figures increases (here they were taking up to 4-5 seconds to make a response)
• the same results were found for depth rotations

Question 7

what is the argument against cooper and shepards mental rotation account?

Answer 7

they used such similar objects (all were different shaped cubes- so there is an extra cost there)

Question 8

What did Shepard and Cooper 1971 say about the mental rotation theory?

Answer 8

it is an analogue transofrmation- meaning you go continuously a bit like a clock rather than jumping from one number to the other

Question 9

what did Shepard and Metzler 1971 find about plane rotation and depth rotation?

Answer 9

they found the same results for plane rotaiton and depth rotation

Question 10

what is their now good evidence for?

Answer 10

people using mental rotation

Question 11

as we know people do use mental rotation, what question should we be asking about mental rotation?

Answer 11

WHEN is mental rotation used

Question 12

what is evidence that we use mental rotation?

Answer 12

some brain areas are activated when you see a rotated object compared to an upright object

Question 13

how did Cooper and Shepard (1973) show that mental rotation is used to achieve object constancy across plane rotation?

Answer 13

• they showed people familiar stimuli (letters) one at a time, and asked is it normal or mirror-reversed?
• it was found the reaction time increased until 180 degrees and then goes down again because you start going back round the other side (graph looks like triangle)

Question 14

when did Jolicoeur 1985 say mental rotation was used?

Answer 14

for mirror-image tasks- also found reaction time gets faster up to 180 degrees and then slower

• they used pictures of two of the same objects and asked if it was left or right facing
• then realised they could just asked people to name the obejct as quickly as possible (people can normally recognise things upside down quickly)

Question 15

what is the problem with the mirror image account?

Answer 15

people do not often have to distinguish mirror images (object recognition tasks are more common)

Question 16

what are the examples of every day mirror images we must distinguish?

Answer 16

• gloves- our hands are mirror images of each other. letters eg b and d (hence why children get these mixed up).
• however, what we really care about is object recognition

Question 17

what is the definitionof parsimony?

Answer 17

using the simplest possible explanation of the data.

Question 18

what has often been assume about both mirror-image and object recognition tasks? (Jolicoeur 1985, Tarr and Pinker 1989 ect)

Answer 18

• mental rotation is used for both mirror-image and object recognition tasks
• this account is parsimonious because it is assumes that a single transformation (mental rotation) compensates for for plane misorientation regardless of the task (mirror- image discrimination or object recognition)

Question 19

what is further indirect support that mental rotation is used for both mirror-image tasks AND object recognition?

Answer 19

studies that have found the effects of plane rotation correlate across mirror-image discrimination and reocognition tasks if the same participants are presented with the same stimuli (jolicoeur 1985 ect)

Question 20

what are the arguments against the account that says mental rotation is used for mirror-image tasks and object recognition?

Answer 20

1. so far this is only weak correlational evidence
2. object recognition does not normally require mirror-image discrimination
3. for familiar objects, plane-rotation costs stay the same despite practice at mirror-image discrimination (Jolicoeur, 1988) whereas plane-rotation costs reduce rapidly with repeated naming
4. worst performance at 180 degrees for mirror- image discrimination but relatively food at 180 degrees for naming

Question 21

what was found about the effect of practice (the third argument against the mental rotation for mirror image and object recognition tasks)

Answer 21

• Jolicoeur 1988 left/right facing image tasks- orientation costs were still there- got a little better over time
• Jolicoeur 1985- horse mirror image task- got much faster between 1st, second and third- the cost for the oreintation changed- very quickly learning to cope with orientation change- practice effects very different between the two tasks. This suggests that mental rotation is not used for both mirror image- tasks and object recognition - proves point number 3 AGAINST the theory

Question 22

how did Jolicoeur 1985 find evidence against the mental rotation account in terms of peformance at 180 degrees? (argument number 4)

Answer 22

she found participants were faster at 180 degrees than any other angle for object recognition task (it should be slowest at 180 because it is a whole object rotation) but they were slowest at 180 degrees for mirror image task- suggest they use different mental processes

Question 23

what does the evidence against the mental rotation account suggest?

Answer 23

• there may be task-related differences in plane rotation costs.
• they provide indirect evidence that mental rotation may not be used for obejct recognition but now we need more direct tests to fully test if mental rotation is used in object recognition aswell as mirror image tasks

Question 24

what three ways have been suggested we can test directly if mental rotation is used in mirror image tasks aswell as object-recognition tasks?

Answer 24

A. compare mirror image (left-right facing) and naming tasks directly (Jolicoeur, Corballis and Lawson 1998)
B. investigate in detail the nature of the orientation function (lawson and joliceour 1998)
C. equate similarity (cheung, hayward and gauthier 2009)

Question 25

how did Jolicoeur, Corballis and Lawson 1998 compare mirror image to naming tasks (argument A)

Answer 25

-used exactly the same stimuli in object naming and mirror image tasks ie used a horse for both rather than using different objects (weren’t able to directly compare). -they tried to push people to rotate in one direction by rotating in 2 degree stages from 120 to 130 to start their mental rotation either clockwise or anticlockwise
- if people do use mental rotation this should push them to rotate the object one way rather than the other
-CW rotation primes fast responses
CCW rotation primes slow repsonses
- it is clear people are mentally rotating - anti clockwise was 150ms slower
-both still slower than doing the task upright
- with the naming task there is a mental cost but doesn’t matter if picture is clockwise or not- did not matter which way you encouraged people to rotate
-conclusion therefore: mirror image tasks use mental rotation but object recognition tasks do not

Question 26

how did lawson and jolicoeur 1998 investigate in detail the nature of the orientation function

Answer 26

-task: word-picture verification- try to identify briefly presented, low contrast, immediately masked pictures of familiar objects
-people good at naming tasks if you show them for long enough so instead they showed images very briefly and faded so very hard to see image
- they then had to type in what image they thought was presented
-almost linear slopes for mirror image task (worst at 180) unlike for naming tasks (instead there is a dip for 180 ie better at 180) but Jolicoeur only tested 60 degrees so the shape of these functions only known coarsely
pictures must be shown about 50% longer if they are plane-misoriented by 120 compared to upright
- again suggested mental rotation is not used

Question 27

what are the conclusions about when mental rotation is used?

Answer 27

-the direct evidence involves:
A. comparing mirror image and naming tasks
B. investigating the shape of the orientation function
C. dissociating the effects of visual similarity and object rotation
- results in all three cases suggest that the visual system uses different processes to compensate for rotations in identification/ recognition tasks compared to mirror image- discrimination tasks
-this suggests that mental rotation is used only in mirror image discrimination tasks and not object recognition tasks
- leaves us with the question of how plane-rotated objects are recognised when mental rotation is not used

Question 28

who proposed there is no cost for plane rotation unless people double check (so view invariant features unless use mental rotation)? (proposal no. 2)

Answer 28

Corballis- he says that once mental rotation is completed people double check because we are not used to seeing the object in this manner- the double checking is what counts as the cost

Question 29

what was Corballis’ 1988 argument for plane rotation?

Answer 29

• he argued that for mirror image discrimination tasks plane rotated views must undergo time consuming transformation (such as mental rotation) this agrees with the research that we have just reviewed
• however corballis claimed that most plane rotated views can be recognised eg named just as efficiently as upright views (he suggested perhaps using view-invariant features)
• corballis argued that plane-rotated views are only named slower than upright in recognition tasks because people double check that they have the right answer before they repsond and that they may use mental rotation to do this before double checking

Question 30

what were the results from corballis’ mental rotation study?

Answer 30

performance becomes flatter as object is rotated because you don’t need to keep double checking that the object is a dog- (when the same image is presented (repeated) three times to participants) as people realise their checking largely unecessary

• he argues that if people do not check there is no cost to recognising plane- misoriented views so his account predicts that plane- rotation costs on naming reduce when stimuli are repeated (Jolicoeur 1985 also produced this result).
• he says this should only affect speeded tasks since double checking should only slow their answers for plane-misorientated views it should not affect accuracy

Question 31

How did Lawson and Jolicoeur test Corballis prediction?

Answer 31

• by briefly showing low contrast, masked pictures of familiar objects in an unspeeded verification task
• contrary to the prediction of corballis’ account object recognition was still worse for plane rotated views
• conclusion: plane rotation costs are not just caused by double checking
• in their study they found the unspeeded task still showed a clear cost of plane- misorientation the first time a picture was recognised
• also effects of practice for this unspeeded task, just like for speeded naming tasks - 50% longer if the object was rotated- suggests it is not double checking- this account is being dismissed

Question 32

what does the 4th account of object constancy for plane rotation suggest?

Answer 32

• store multiple views for each familiar object; only transform stimuli if they are presented at an unfamiliar view
  -that usually we store upright views of objects- when we see a plane rotated view that is probably the first time we have seen it- we need to transform the image to uprigtht representation
  but if we keep seeing these different views of the horse then we will start storing these different views then we can directly match to stored template- multiple views plus transformation account provides a good explanation of most of the data we have discussed.. but what transformation is used?

Question 33

what are the conclusions for object constancy for plane rotated objects?

Answer 33

• most theories of how we achieve object constancy for plane rotation only seem to apply in restricted cases:
  1. mirror image discrimination may use mental rotation.. but object recognition does not seem to
  2. identifying view invariant features can achieve object constancy, but only in special cases. this strategy is most useful for repeatedly recognising small sets of distinctive objects- but this is rare in everyday life. also double checking does not seem to provide a parsimonious account of how plane-misoriented pictures are recognised
  3. with practice, multiple views of an object at different rotations are probably stored. storing these multiple templates reduces the costs of plane rotation for familiar views
  4. but how are novel views identified if mental rotation is not the transformation used?