Lecture 15

Aging and Motor Development

Theories on Aging

• Welford's Neural Noise Hypothesis (1981)
  • System is made up of signals and noise
  • Filter out noise
  • Older adults have more noise in the system, thus it takes longer for them to respond
  • Signal to noise ratio
• Cerella's Neural Net Model (1990)
  • System is composed of nodes (axons) and links (connections between neurons)
  • In a normal system the time between input and output is the time needed to traverse the nodes and links
  • In older adult, some of the nodes are broken, thus it takes more time for the signal to get through (longer path to travel)
• Salthouse (1985) proposes several possibilities
  • Input/Output rate
    • Slower rate of transmission of information
  • Software Differences
    • Functional mechanisms (strategies, decision making, memory)
  • Hardware Differences
    • Central or structural mechanisms
• All explanations have been used to explain differences between young and older adults

Motor Skills Studied in Older Adults

• Posture, Balance, Locomotion
  • Important because of the practical aspects
  • Can predictions be made about "fallers"
  • Balance requires more conscious effort in later life
  • Important findings
    • Older adults have more body sway (Woollacott & colleagues)
    • Slower recovery of balance when falling (Stelmach & colleagues)
    • Reduced sensory input (Teasdale & others)
  • Locomotor patterns resemble those of small children
  • Out-toeing, steps, swing/stance ratio

Exceptions to Slowing with Age

• Are the effects of aging inevitable? Can the effects be slowed or reversed?
• Practice or experience
  • Salthouse (1985) has demonstrated that in skills in which experienceis a factor, older adults do fairly well (typing tasks)
  • RT Tasks where voice, rather than manual response is used (Salthouse & Somberg, 1982)
  • If older adults are given sufficient practice and enough time, they can be successful
    • Cross-sectional research problems (Cohort)
• Exercise can slow the effects (reverse??)
  • Spirduso has demonstrated that older active adults are similar in SRT, CRT, & MT to young adults (need for longitudinal studies)
  • Maintenance of some type of exercise or physical skill is important in older age
  • Training studies have demonstrated that exercise programs can
    benefit untrained, inactive older adults (Fitarone, Bassey)
  • Meyer, Goggin, & Jackson (1995) found that healthy older women were stronger, and displayed superior quality of movement when compared to frail older women

Speeded Activities

• Reaction Time
  • Older adults are slower and have difficulty as task increases in complexity
  • Response Preparation (RT)
    • Do older adults use advance information?
    • Stelmach, Goggin, & Garcia-Colera (1987) demonstrated that older adults do not use advance information as efficiently
    • Goggin & Stelmach (1990) found that older adults do use advance information to prepare
    • Skill didn't involve component of accuracy
  • Response Selection (decision making)
    • Older adults are more affected by # of S-R alternatives, S-R Compatibility, but have been shown to improve capabilities (videogame playing)
  • Response Programming (muscle commands)
    • Stelmach, Goggin, & Amrhein (1988) found that older adults plan, prepare and reprogram movements similar to young subjects, but are slower
  • Response Complexity
    • Bimanual coordination is not as efficient in older adults (Stelmach, Amrhein, & Goggin, 1988)
• Movement Time (MT) Mechanisms
  • Older adults are slower in movement
  • One way to examine effects of aging on MT is to use the speed-accuracy tradeoff manipulation
    • Older adults prefer to operate at a speed that allows them to successful
    • Slow down to be accurate (Salthouse, 1988)
    • Almost always commit fewer errors in experiments (Goggin & Meeuwsen, 1992)
      • Young (8.45%) / elderly (5.36%)
    • Commit errors of omission--fail to respond, rather than be wrong

Kinematics and Speed-Accuracy Trade-off

• Examine the response characteristics of the movement
• Separate movement into two phases, initial open-loop phase, and feed-back, closed-loop phase (Woodworth, 1899; Fitts, 1954)
• Goggin & Stelmach (1990)
  • Older adults have difficulty scaling velocity to match movement distance
  • Small peak velocity
  • Longer deceleration phase (little accuracy component)
• Goggin & Meeuwsen (1992)
  • Older adults displayed longer MT, and were more affected by ID
  • Velocity and acceleration profiles of older adults were significantly different from young

Can you teach an older adult new skills (tricks)?

• Strategies or suggestions for working with older adults
  • Preparation for learning
    • Explain task importance; treat with respect
    • Don't give too much information
  • Make environment conducive for performance
    • Proper lighting, temperature
    • Eliminate extraneous stimuli
  • Provide cues, attentional strategies
  • Encourage them to prepare the movement in advance