PPA case studies

Question 1

Agnosia: can describe an object well but only guess its function from the description “it could be a change purse for coins of five sizes” [gloves]

Answer 1

Dr P

Question 2

Agnosia: can describe an object well but only guess its function from description. “It does not seem logical unless it is some sort of brush” [carrot]. “A soup ladel” [drawing of a nose].

Answer 2

HJA

Question 3

Agnosia: failed the Efron task and couldn’t represent shapes, but she was able to process shapes for actions e.g. she couldn’t understand the orientation of a letter hole, but she could post a letter through it. She accurately moved her fingers to pick up objects but couldn’t draw them. There is subliminal motor-calibration but no access to this knowledge.

Answer 3

DF [35 yo, F, CO poisoning to posterior cerebral lesions]

Question 4

Agnosia: no apperceptive agnosia, fine vision, fine ability to verbally describe objects, their relative size, etc. But he could not match words to pictures, say what pictures were of larger/smaller objects, or pick out real from fictional objects. Strangely, he was better at object decision task when only using silhouettes, maybe less information helps?
the ability to access semantic knowledge verbally but not visually suggests that the knowledge is still there but can only be accessed through other modalities.

Answer 4

FRA [77 yo, M, left hemispheric stroke in occipital lobe]

Question 5

Agnosia: could match objects but couldn’t answer “what tool is used to chop wood?” so had semantic access agnosia. If semantic knowledge is damaged, then no modality will be able to access knowledge.

Answer 5

HO [Herpes Simplex Encephalitis causing lesions of temporal lobe]

Question 6

Prosopagnosia: faster at matching celebrity faces to names if the celebrity is of the same industry e.g. matching Gordon Brown to a politician’s face is better than a presenter’s face. Knowledge of the face and the industry may interfere with the association suggesting subliminal recognition.
Poor at recognising cars and flowers

Answer 6

PH

Question 7

Prosopagnosia: had prosopagnosia but was able to distinguish the faces of sheep. This suggests that prosopagnosia is not simply the result of impaired visual distinction because they wouldn’t be able to distinguish any faces if it were. Face processing is separate to other processing.

Answer 7

WJ

Question 8

Prosopagnosia: can name categories of complex novel objects. Recognition issues was confined to faces, so facial recognition is a distinct deficit.

Answer 8

FB [Unilateral right hemisphere lesion]

Question 9

Prosopagnosia: poor at recognising faces but also poor at recognising four-legged animals.

Answer 9

LH

Question 10

Blindsight: Patient was unable to consciously see but could avoid objects when walking and ‘guess’ where things were.

Answer 10

TN

Question 11

Blindsight: heminopia but signs that he could see in the blind field. He could guess a horizontal or vertical stick in blind field and he could detect movement when just guessing (93% accuracy though).

Answer 11

DB [removed striate cortex]

Question 12

Blindsight: couldn’t see things on the right but could accurately guess the direction of moving objects.

Answer 12

GY

Question 13

Planning: frontal lobe damage made him vulgar, abandon future plans, say false things. This reflects issues with social reasoning and planning.

Answer 13

PHINEAS GAGE [25 yo, M, frontal lobe damage]

Question 14

Planning: operation caused social difficulties, relationship difficulties, money issues, deciding what to wear, planning the day.

Answer 14

EVR [meningioma removed causing damage to frontal loves

Question 15

Planning: severe disorganisation in everyday life but performed well in WCST, stroop task, verbal fluency, and tower of London test.

Answer 15

AP [23 yo, M, bi-frontal damage]

Question 16

Apraxia: couldn’t imitate simple hand movements e.g. ‘ok’ sign, or pantomimes with right hand. But he could with his left hand. This shows there is comprehension of the task, just inability to plan the action.

Answer 16

MT

Question 17

Apraxia: difficulty imitating and pantomiming

Answer 17

MJC [left parietal skull fracture]

Question 18

AHS: Suffered ruptured aneurysm which damaged the corpus callosum. He experienced tug of war between he two hands; one hand would do one action, and the left hand would do the opposite

Answer 18

MP

Question 19

AHS: developed AHS, unresponsive to voluntary commands.

Answer 19

JC [stroke, damage to frontal area and corpus callosum]

Question 20

Benton and Van Allen

Answer 20

described a prosopagnosia patient who performed ok with unfamiliar faces but not with familiar faces suggesting the model is indeed hierarchical.

Question 21

Benton

Answer 21

also described a patient who could recognise familiar faces but was unable to process unfamiliar faces which is the opposite

Question 22

Kurucz and Feldmar

Answer 22

described patients who could recognise familiar faces but not understand expressions.

Question 23

Bornstein and colleagues

Answer 23

described a prosopagnosic birdwatcher who lost the ability to distinguish birds, and a farmer who lost the ability to distinguish cows.
These are taken as evidence that prosopagnosia is a result of general visual recognition systems.

Question 24

Dankert & Rossetti

Answer 24

• Agnosopsia (type 1) – no awareness but can guess perceptual characteristics well. Linked to projections that terminate in the ventral area.
• Attention-blindsight (type 2) – can sense stimuli, motion, and discriminate.
• Action-blindsight – can point and interact with objects in blind field. Linked to visual projections that terminate in dorsal extrastriate area.

Question 25

Kolb & Braun

Answer 25

superimposed vision and found that participants with normal vision were only able to find a target when guessing. 75.2% accuracy.

Question 26

Moray

Answer 26

participants had no memory of words in the unattended ear even when repeated 35 times.
participants recognise their name in the unattended message which suggests that at least some of the information from the unattended ear makes it through to the attended information. This has been replicated.

Question 27

Corteen and Wood

Answer 27

conditioned words to an electric shock. They found that participants had skin conductance when the words were presented in the unattended ear, but also for related words e.g. Paris if London had been conditioned. This shows that the unattended message is being processed.

Question 28

Grey and Wedderburn

Answer 28

we group the meaning of sentences and report them consistently with meaning e.g. digits and words result in participants merging “mice eat cheese” from the two streams rather than “mice three cheese”.

Question 29

Deutsch and Deutsch

Answer 29

we process everything that we sense, and we select which input to attend and respond to just before we respond to it rather than filtering out any input along the way.

Question 30

Treisman

Answer 30

when you switched the message in the channels, participants automatically switch their shadowing before they realise and switch back to the attended ear. This suggests they process the switch in the content and attenuate the irrelevant messages. They therefore process all messages and just ‘turn down’ the unattended one.

Question 31

Johnson and Heinz

Answer 31

We may have limited capacity and the extent of attenuation depends on how much attention and concentration is being use in alternative tasks. Hence, we are more likely to notice changes in the unattended ear if the attended task requires little concentration

Question 32

Lavie

Answer 32

attention depends on the perceptual load of the task at hand. Other information slows response speed because extra information distracts you.