Action Preparation

1
Chapter 8

• Action Preparation

Concept Performing voluntary, coordinated
movement requires preparation of the motor
control system
2
The Question of Interest in this Chapter

• What does the motor control system do when we
  get ready to perform an action in a specific
  situation?
• Action Action Action
• Intention Initiation Termination

Preparation
3
Action Preparation Requires Time

• Donders (1868), Dutch physician, began the
  research that demonstrated the need for time for
  the motor control system to prepare to produce an
  intended action
• RT (reaction time) is the commonly used index of
  the preparation time required to produce action
• Based on findings showing that RT is influenced
  by many performance situation and performer
  characteristics

4
Task and Situation Characteristics Influencing
Preparation

• Number of response choices
• Hicks Law
• RT increases logarithmically as the number of
  stimulus-response choices increases See Fig. 8.1

• 2. Predictability of the correct response choice
• RT decreases as the predictability of the correct
  response choice increases

5
Task and Situation Characteristics Influencing
Preparation, contd

• 3. Influence of the probability of precue
  correctness
• Precue an advance indication that a specific
  upcoming event will require a response
• Faster RT if probability of precue correctness is
  higher than if probabilities of possible choices
  are equally possible
• e.g. 2 choices Right 80 Left 20
  compare with 50 50
• Cost benefit trade-off for biasing anticipated
  required response to the higher probability (if lt
  100) See Fig. 8.2

6
Task and Situation Characteristics Influencing
Preparation, contd

• Stimulus-response compatibility
• RT decreases as the spatial relationship between
  a stimulus and its response increases
• Stroop effect
• Spatial arrangement of stimuli and their
  associated response mechanisms
• e.g., Stove top example see A Closer Look
• Foreperiod length regularity
• RT increases/decreases as a function of the
  length and the regularity of the length of the RT
  foreperiod
• i.e., interval between warning and go signals

7
Task and Situation Characteristics Influencing
Preparation, contd

• Movement complexity
• RT increases as amount of complexity of the
  action increases
• First demonstrated by classic experiment by
  Henry and Rogers (1960) See A Closer Look
• Movement accuracy
• RT increases as movement accuracy demands of the
  action increase
• First demonstrated by evaluating RT results for
  Fitts tapping tasks with different Indexes of
  Difficulty (i.e. as MT increased, RT also
  increased)

8
Task and Situation Characteristics Influencing
Preparation, contd

• 8. Repetition of a movement
• 9. Time between different responses to different
  signals
• Delay of response to 2nd stimulus (signal)is
  called the psychological refractory period (PRP)
  See Figure 8.3
• Relate to a situation in sports involving a
  fake movement followed by the intended movement
  as the 2 stimuli and the other players responses
  as the 2 responses

9
Two Performer Characteristics Influencing
Preparation

• Alertness of the performer
• Warning signal effect
• Foreperiod length effect See Fig. 8.4
• Vigilance effects
• Attention focused on the signal vs. the movement
• RT benefits more from focusing on the signal
  (e.g. sprint start in swimming)

10
Motor Control Events That OccurDuring Preparation

• Postural preparation
• Organization of movements needed for postural
  support
• Anticipatory characteristic of movement activity
  involved in postural preparation
• Flexible synergistic organization characteristic
  of postural movement preparation

11
Motor Control Events That OccurDuring
Preparation, contd

• Limb performance characteristics
• e.g. Movement
• Direction
• Trajectory
• End-point accuracy (i.e. for a ballistic movement)

• Object control characteristics
• Force control
• End-state comfort position (i.e. hands final
  spatial position as initial position)

12
Motor Control Events That OccurDuring
Preparation, contd

• Sequences of movements
• See research on piano playing as evidence
• Spatial coding
• Evidence from S-R compatibility research

• Rhythmicity preparation
• Preperformance rituals
• See examples in Table 8.1
• Research shows they appear to prepare relative
  timing of upcoming movements