In-Depth Notes on Touch, Movement, and Memory

Touch (Haptic Perception)

  • Important for providing feedback about the environment
  • Especially crucial for individuals who are visually impaired
  • Touch stimuli received through the skin, which has three types of sensory receptors:
    • Thermoreceptors: Respond to heat and cold
    • Nociceptors: Respond to intense pressure, heat, and pain
    • Mechanoreceptors: Respond to pressure

Mechanoreceptors

  • Two types of mechanoreceptors based on pressure response:
    • Rapidly adapting mechanoreceptors:
    • Respond to immediate pressure as skin is indented
    • React quickly to increased pressure but stop responding to continuous pressure
    • Slowly adapting mechanoreceptors:
    • Respond to constant pressure over time

Touch Sensitivity Threshold Test

  • Procedure: Hold two pencils 12 mm apart and lightly touch thumbs with both
    • Adjust distance until both points are felt
  • Sensitivity Measurement:
    • Smaller distance = higher sensitivity
    • Larger distance = lower sensitivity

Touch Acuity Measurement

  • Sensitivity on different body parts varies significantly:
    • Forearm sensitivity is approximately 10 times less than fingers/thumbnails
    • Fingers and thumbs exhibit the highest acuity

Kinesthesis

  • Awareness of body and limb positions supported by:
    • Receptors in joints:
    • Rapidly adapting receptors: Respond to limb movement direction
    • Slowly adapting receptors: Respond to movement and static position
    • Positional receptors: Respond only when a limb is static
  • Kinesthetic awareness is crucial for tasks requiring fine motor skills (e.g., touch typing)

Movement and Motor Control

  • Definitions: Movement time = Physical movement duration + Reaction time
  • Influenced by factors:
    • Age and fitness of individuals
    • Reaction time varies depending on sensory channels:
    • Visual: ~200 ms
    • Auditory: ~150 ms (fastest)
    • Pain: ~700 ms (slowest)
  • Combined signals yield quicker responses

Accuracy in Motor Skills

  • Speed of reaction can impact accuracy, with the following implications:
    • Increased reaction time can sometimes improve accuracy
    • In gaming, less skilled users might falter on fast-paced tasks
  • Studies show faster keyboard operators perform better but with fewer errors than slower ones

Interaction System Design

  • Speed and accuracy are critical for creating user-friendly interactive systems
  • Time taken to navigate to targets (buttons, icons) affects user experience

Memory Overview

  • Memory includes:
    • Preservation of experiences, knowledge, and identity
  • Types of Memory:
    • Iconic Memory: Brief visual retention (e.g., visual traces from fireworks)
    • Echoic Memory: Brief aural retention (e.g., recollection after being distracted)
    • Haptic Memory: Memory specific to touch

Short-Term Memory

  • Acts as a temporary information storage (70 ms access, 200 ms decay)
  • Typical capacity is 7 ± 2 items (Miller's Law)
  • Chunking: Organizing information into manageable units enhances capacity
    • Example: Individuals better recall chunked sequences, improving memory retention

Long-Term Memory

  • Types:
    • Episodic Memory: Personal experiences (when and where events occurred)
    • Semantic Memory: General knowledge about the world (conceptual facts)
  • Information transfers from short-term to long-term memory via rehearsal

Memory Encoding, Storage & Retrieval

  • Encoding: Involves rehearsal and strategies like spaced learning
  • Storage: Categorization and organization improve retention
  • Retrieval: Can be aided by cues and contextual reminders
    • Recall involves reproducing information; Recognition confirms familiarity with previously encountered material.