HCI 440

Fall 2022

Craig Miller

Weekly Notes

Assignments

Psychological Fundamentals for HCI

Human cognition is often understood in terms of a model of information processing.

Most of this information is presented in The Psychology of Human-Computer Interaction by Card, Moran and Newell.

Also see The Programmer's Brain by Felienne Hermans.

Central Cognition

  • Short-term memory (STM) and working memory (WM)
    • WM includes STM (according to some sources)
    • Limited approximately 3 chunks
    • Includes perceptual and motor stores
    • Triggers access to long-term memory (LTM)
    • LTM acts on WM
  • Long-term memory
    • Essentially unlimited
    • Associative
    • Acquired through active usage of working memory
    • Organizes information in chunks
  • Cognitive processor
    • Applies long-term memory to modify working memory
    • Operates at approximately 70 msec cycles
    • Conscious versus unconscious cognition

Input/Output

  • Perception
  • Motor processor
    • approximately 70 msec cycles
    • Fitts' law (in H&P 22.7, 30.3.2.5 in second): Pointing time (seconds) = log2 (distance / size + 1)

Important cognitive principles

  • Recognition is easier than recall (near misses can trigger LTM)
  • STM/WM limits multi-tasking
  • Practice creates procedural knowledge for automatic behavior

Time scales

Adapted from Unified Theories of Cognition, Allen Newell

  • Biological band (neurons and circuits, faster than 10 ms)
  • Cognitive band (cognitive operations, 100ms to 10 seconds)
  • Rational band (Tasks, minutes to hours)
  • Social band (days to months)

Constants for keystroke-level model

  • K = 0.2 sec Keying: the time it takes to tap a key on the keyboard or a button on the mouse.
  • P = 1.1 sec Pointing: the time it takes to move the mouse to a position on the display.
  • H = 0.4 sec Homing: the time it takes to move the hand from the keyboard to the mouse or from the mouse to the keyboard.
  • M = 1.35 sec Mental preparing: the time it takes to mentally prepare for the next step.
  • R Responding: the time needed for the computer to respond.

High-level psychological constructs

  • Mental Models
  • Metaphors

Issues for discussion

  • What are examples of automatic procedural behavior?
  • What do the keystroke constants suggest for developing an efficient user interface?