Cognition of purposeful action

1. Cognition of purposeful action • Overview • the focus of this lecture is on the performance of skilled action in a variety of situations • how does knowledge/memory get converted into action? • How does this knowledge get encoded into memory?

2. Cognition of purposeful action • Effects of practice on performance • it is well established that skilled performance improves with practice • but how should we conceptualize this change?

3. Cognition of purposeful action • Singley & Anderson (1989) • studied development of text-editing skill • participants were secretarial students who were skilled typists, but had not yet used word processors • given practice over 6 days, 3 hours/day editing a written manuscript containing 6 changes per page

4. Cognition of purposeful action • Singley & Anderson (1989) • Dependent variables • measured total time to make edits • thinking time: whenever more than 2 seconds elapsed between successive keystrokes • keystroke time: whenever less than 2 seconds elapsed between keystrokes

5. Cognition of purposeful action • Singley & Anderson (1989) • Results • most of the improvement is a result of a reduction in thinking time • keystroke rate did not change substantially • in other words skill acquisition starts out with a large cognitive component that decreases with practice

6. Cognition of purposeful action

7. Cognition of purposeful action • Generalization • this and many other studies suggest that skill acquisition starts out with a large cognitive component that decreases with practice • eventually with enough practice the cognitive component of practice is squeezed out entirely and there is only an automated motor routine

8. Cognition of purposeful action • Power law of learning • many studies have investigated how memory improves with massive amounts of practice • e.g., Pirolli & Anderson (1985) • subjects practiced memory for 15 sentences for 25 days, 2 hours per day

9. Memory for actions • Pirolli & Anderson (1985) • e.g., targets. The doctor hated the lawyer; the radical touched the debutante; the sailor shot the barber • e.g., lures. The doctor touched the barber; the radical shot the lawyer • Results • time to make a recognition judgement; improvement is rapid initially, but rate of improvement slows down with amount of practice

10. Memory for actions • Results • When the data are plotted on a log-log scale the data are fitted very well by a straight line • in other words you take the log of recognition time and the log of days of practice • What this means is that the relation between practice and performance is fitted by a power function

11. Memory for actions • Results • Power law of learning because the function is a power function • Time to Respond = Practiceb • T = 1.40 P -.24 • Note: • ln T = ln 1.40 -.24 ln P • ln T = .34 -.24 ln P

12. Memory for actions • The power function of learning appears to fit to a wide variety of complex skills • e.g., Asimov’s writing skill appears to be fit by a power function • Asimov wrote 500 books over a 40 year period • he sat at his keyboard every day from 7:30 am to 10:00 pm • What this means is that his speed of writing books increased throughout his career

13. Cognition of purposeful action • Stages of skill acquisition • Fitts (1964) proposed that skills go through three stages as they develop • cognitive: work from instruction or an example; use of verbal cueing prominent • associative: more direct representation of what to do; probably still verbal • autonomous/automatic: cognitive involvement drops

14. Cognition of purposeful action • Stages of skill acquisition • cognitive stage • conceptualized as a type of problem solving • how is it that people can go from some initial limited factual information to their first solutions of problems in that domain? • E.g., learning to apply salve to both hands if you are hemiparetic (Goldenberg) • e.g., learning to use a novel tool (Goldenberg)

15. Cognition of purposeful action • Stages of skill acquisition • overview of problem solving • Newell & Simon conceptualize problem solving as consisting of using operators to achieve goals • operators are procedures for changing a current situation into something that is closer to goal

16. Cognition of purposeful action • Stages of skill acquisition • types of operators • difference reduction: apply an operator that moves you closer to goal state • e.g., cockroaches flee light, people cook meals by selecting steps that bring them closer to cooking a meal

17. Cognition of purposeful action • Stages of skill acquisition • types of operators • operator subgoaling: when trying to achieve a goal, there are times when a precondition of applying an operator is not satisfied; then need to set a subgoal of achieving the precondition • e.g. bicycle tire soft; goal: inflate tire; failed precondition (no bicycle pump); subgoal, find bicycle pump

18. Cognition of purposeful action • Stages of skill acquisition • Associative stage • as people become practiced in a skill, they recognize directly what they had to think through • Logan (1988) proposed that as people become practiced, they learn a solutions to problems, which are stored, and then can be retrieved directly • no longer solve problem, but retrieve needed information

19. Cognition of purposeful action • Stages of skill acquisition • Associative stage • Raichle, Fiez, Vidden, MacLeod, Pardo, Fox, Peterson (1994) • generate associates to a word like apple • this task is repeated several times; with practice people give the same response (e.g., peel) • brain activation: anterior cingulate and other frontal areas initially; with practice, more posterior regions of brain are activated

20. Cognition of purposeful action • Stages of skill acquisition • Autonomous stage • characteristics: requires less attention; difficult to interrupt; may not be accessible to consciousness • motor program: a prepackaged sequence of actions • signing your name • making a hammering action

21. Memory for actions • Motor programs • open-loop versus closed-loop performance • closed-loop system: wait for feedback from one action before performing next action • open-loop system: execute a sequence of actions before checking to see whether earlier actions achieved their intended effects • 3 lines of evidence that motor programs are open-loop at the cortical level

22. Memory for actions • Motor programs • evidence that motor programs are open-loop at the cortical level • slowness of closed-loop behaviour (200 ms simple RT) • e.g., skilled typists, pianists, violinists etc. execute action sequences much too quickly • movements appear to be planned in advance • e.g., time to initiate typing of a word increases with word length; movements cannot be easily stopped once initiated

23. Memory for actions • Motor programs • e.g., movements cannot be easily stopped once initiated • Slater-Hammel (1960) had subjects view a sweep timer that made one revolution per second; task, stop timer when it reached a certain position by raising finger from a key • evidence suggests that you need to send a signal at least 250 ms before it reached target; if sweeper stopped less than 250 ms on its own subjects could not stop their finger from moving

24. Memory for actions • Motor programs • deafferentation studies of monkeys • these studies eliminate sensory input by cutting through dorsal roots of the spinal cord • this eliminates all sensory feedback from the limbs although movement is unimpaired • results: animals can learn new movements and can perform them successfully after they are learned in the dark

25. Memory for actions • Motor programs • motor programs are general, not specific sequences of behaviour • e.g., people can write with different limbs (hands, feet, mouth) • e.g., hammering can take place on different planes

26. Memory for actions • Motor programs • learning of motor programs • Keele has proposed that new motor programs are learned by stringing together individual actions that are under individual control so that with practice sequences of actions become bundled together into a motor program that can be executed without outside control

27. Memory for actions • Motor programs • Jenkins, Brooks, Nixon, Frackowiak, & Passingham (1994) performed a study in which subjects learned to push a sequence of 8 buttons using PET • Results showed that early on the lateral prefrontal area and the posterior parietal cortex were active, whereas with practice the supplementary motor area and hippocampus were active

28. Memory for actions • Motor programs--Schema theory • Schmidt hypothesizes that the learner develops to representations of a skill • recall memory: the motor program itself • recognition memory: representation of the desired outcome of the action -- response-produced feedback and external sensory consequences

29. Memory for actions • Motor programs--Schema theory • Schmidt hypothesizes that recall memory (the motor program) is improved by comparing the action produced to the internal standard of recognition memory • this implies that recall memory can improve even when there is no external feedback

30. Introduction • Apraxia • inability to perform skilled or learned movements that cannot be attributed to a language comprehension disorder, an elementary motor deficit, or a sensory deficit

31. Brief, selective historical review • term coined in 1871 by Steinthal; agnosia • Liepmann in early 1900s formulated the original description of apraxia • skilled movement was primarily mediated through left hemisphere • ideational apraxia, a disruption of the idea or the representation of the plan of the movement and • ideomotor apraxia, plan is intact, but it cannot be implemented or produced

32. Symptoms of Apraxia • Conceptual apraxia • errors in tool selection or use • impaired recognition of gestures • impaired in producing sequence of actions

33. Symptoms of Apraxia • Ideomotor apraxia (cont’d) • errors in spatial or temporal aspects of actions • impaired imitation and performance to command • Kinematic analyses show abnormal joint angles and abnormal kinematics in tool use • Deficits in declarative knowledge of manipulation actions, mechanical problem solving, and difficulty learning new actions

34. Learning from viewing • How can new actions be learned when they are viewed? • To answer this question, I’ll begin with a review of the dorsal and ventral visual streams • Then afterward will postulate the existence of two separable streams, a grasp-to-use system, which is impaired in apraxics and a grasp-to-move system, which is impaired in optic ataxics

35. Dorsal and Ventral visual streams

36. Ventral and Dorsal Streams • Ventral stream (what stream) • Associated with object recognition and form representation • Connected to medial temporal lobes and dorsal stream • Dorsal stream (where/how stream) • Function of dorsal stream less certain\ • Originally thought to be associated with spatial awareness and spatial grasping • Goodale and Milner proposed it is associated with how-to-information

37. Limitations of ventral-dorsal model • It has been argued by some investigators (e.g., Buxbaum) that the dorsal stream is overly simplistic and that there are two different dorsal streams • One stream is specialized for grasp-to-move; the other for grasp-to-use an object • Grasp-to-move- moving an object (e.g., hammer) with your hand from one location to another • Grasp-to-use – picking up and object with the intention of using it (skilled use or manipulation of the object)

38. Grasp-to-use Imagining, planning, or making judgments about skilled use Hand postures are skilled Postures based on internal models Intrinsic frame of reference Ideomotor apraxics have damage to this system Grasp-to-move On-line system that enables one to reach and grasp objects Adjustments based on visual system Hand postures based on structural characteristics of object (external) Extrinsically driven Optic ataxics have impairment to this system Two dorsal routes

39. Support for two dorsal route model • It has been shown that ideomotor apraxics are impaired on pantomime of skilled gesture, recognition of skilled gesture, and skilled gesture use • However, there is evidence that px with skill gesture use impairment may have intact grasp-to-move • Conversely px with optic ataxia (an impairment in visually-guided reaching) may be intact in skilled grasp-to-use (see Buxbaum, 2006 for a review)

40. Representational model of apraxia • The next slide shows the representational model of apraxia • An important feature of this model is that it postulates skilled actions may be mediated (semantically) • In addition, note that skilled actions can result directly from a visual input to a motor program • Thus, according to this model it may be possible to produce skilled actions without semantic knowledge of the action

41. Visual/Gestural input Visual/Object Input Visual analysis (motion) Visual analysis (static) Action input lexicon Structural Description System Auditory/ Verbal Input Tactile Analysis Tactile/ Proprioceptive Input Semantic knowledge Auditory analysis Action output lexicon Motor programmes Representational model of praxis (from Chainay & Humphreys, 2002)

42. Support for conceptual vs ideomotor distinction • As described in the next slides there is evidence that conceptual action impairment and ideomotor apraxia dissociate • As will be reviewed some px with ideomotor apraxia may not have conceptual action knowledge impairment (Ochipa, 1992) • Also, it has been reported that px with conceptual action impairment may not have gestural impairment (Riddoch & Humphreys, 1987)

43. Case study Ochipa et al. 1989 • History • 67 year old left-handed male • high school education • sudden onset of left hemiparesis & speech difficulty • CT scan 1 week post onset showed infarct in right middle cerebral artery involving frontal, superior temporal, and inferior parietal lobes

44. Case study Ochipa et al. 1989 • Reason for referral • investigate the reason for why patient showed inappropriate use of actual tools in hospital environment (e.g., eat food with a toothbrush) • Tests administered • Western Aphasia Battery • Praxis Test Battery

45. Case study Ochipa et al. 1989 • Results • unable to identify tool when function described (7/20) • unable to describe verbally function of tool given a visual picture of tool (3/20) • pantomime to command (0/20) (errors: no response or irrelevant movement; not production) • pantomime to imitation extremely poor (4/20) • performance improved only marginally when allowed to hold tools prior to gesturing tool fx

46. Case study Ochipa et al. 1989 • Conclusions • inability to perform a skilled movement-- yes • not attributable to language comprehension problem (WAB; can point to tool given name) • not attributable to a sensory problem (can name tool given picture) • results suggest there was a loss of knowledge about the function of a tool, and the actions associated with a tool

47. Semantic or Conceptual Memory • Semantic memory • composed of knowledge about the world including facts, concepts, and beliefs • knowledge is shared by a culture rather than episodic or autobiographical memories that are unique to an individual and tied to a specific time or place • How should we conceptualize semantic memory and what relation does it have to praxis?

48. Action semantics • knowledge of the function of tools and objects • tool, used to provide mechanical advantage in an action; • object, recipient of an action • knowledge of actions independent of tools, the association between tools and actions, and the association between tools and objects • mechanical advantage of tools

49. Action semantics • Action semantics (cont’d) • knowledge about the organization of single actions into sequences • knowledge of symbolic meaning of actions

50. Conceptual apraxia empirical • Ochipa et al. (1992) • Purpose: a) to determine whether AD px have conceptual apraxia; and b) whether conceptual apraxia can be dissociated from linguistic semantics and praxis production • Method • 32 px with prob AD (NINCDS-ADRDA criteria); and equal number of intact controls