Engineering Models of Human

Behavior & Information Processing

Objective is to present an integrated description of human performance

(as it relates to human –machine interactions)

Scale Relationships in the Human Processor

Engineering Model of the Human System:

Input Black BoxOutput

Input: Perceptual System

  • Visual
  • Auditory
  • Tactile
  • Olfactory (smell/taste)

Output: Motor System

  • Voluntary muscle groups

Black Box: Cognitive System

Each can be thought of as: a Processor + Associated Memory

Thus, for the Perceptual System, these can be thought of as sensors having associated buffer memories

(buffer memories hold the output of the perceptual subsystem while it is being symbolically coded):

  • Vision can be modeled as: Visual processor + visual image store (working memory)
  • Auditory: Auditory processor + auditory image store
  • Tactile: Tactile processor + tactile image store
  • Olfactory: Olfactory processor + olfactory image store

For the Cognitive System: Cognitive processor + Working memory & Long-term memory

(and interactions between them)

For the Motor System: Motor Processor + Access to working memory

Processors and Memory have quantifiable characteristics and attributes:

Discriminatory Principle of Perceptual Events (P3) : leads to the concept of a cycle time, 

Perceptual events occurring within a single processing cycle are combined if they are sufficiently similar.

Observations:

Two lights occurring in a nearby location within 60-100 msec. appear as a single light in motion.

Brief pulse pulses of light within pseconds appear as a longer pulse of less intensity

Rapid set of clicks leads to a fusion of clicks – basis of Morse Code

Block’s Law: For t < p: perception ~I(t)dt where I is the perceived intensity of the stimulus, I(t) the intensity over time

2nd order effect: p is not realy constant but decrease with more intense stimuli

Processors: Cycle time, (unit impulse response)

Type / Cycle time ,  (sec.) nom. [slow man – fast man]
Visual / 0.10 [0.050 – 0.20] (stimulus impinges retina at t=0, at t = image available in image store. (can “see it”, like a “photographic process”). Time is involved! Motion is available sooner.)
Auditory / 0.10 [0.090 – 0.11]
Motor / 0.07 [0.030 – 0.10]
Cognitive / 0.07 [0.025 – 0.17]

Movement is not continuous but consist of a series of discrete micro movements.

Movement is a result of rapid firing of opposing “agonists’ and “antagonists” muscle pairs fired one shortly after the other

Motor processor issues open-loop draw command every p , Perceptual system checks to stay btwn lines, p , which sends it to the cognitive system , c , which leads to corrections in the “open-loop command issued by the Motor system, m . Visual feedback is made in p + c + m = 240msec

Memory:

Perceptual Memory accepts the physical stimulus and begins to transfer it to working memory. This process takes time. If the stimulus is presented for too short of a time or is too complex, then its trace fades before it can be transferred to working memory. Memories also have storage capacities .

Decay time half-lifeStorage capacity (items), Main Code Type (physical, acoustic, visual, semantic), 

Type

/

Decay time, (sec.)

/ Storage capacity, (items) / Code type, 
Visual image store / 0.2 [0.09 – 1.0] / 10 [7 – 17] letters / physical
Auditory image store / 1.5 [0.9 – 3.5] / 5 [4.4 – 6.2] letters / physical
Working memory / 7 [5 – 226] / 7 +/- 2 chunks / symbolic (unaffected by intensity)
Long-term memory / ”infinite” / f ( associations) / semantic

Working Memory can be thought of as subsets of Long-term Memory that has become activated

Principles Of Operation

P0. Recognize-Act Cycle of the Cognitive Processor. (perceptual-cognitive-motor)

P1. Variable Perceptual Processor Rate Principle. p varies inversely with stimuli intensity

P2. Encoding Specificity Principle. Specific encoding operations on what is perceived determine what is stored. What is stored determines what retrieval cues are effective in providing access to what is stored.

P3. Discrimination Principle. The difficulty of memory retrieval is determined by the candidates that exist in memory relative to the retrieval cues.

P4. Variable Cognitive Processor Rate Principle. c varies is shorter when there is more pressure and reduces with practice.

P5. Fitt’s Law. Recognize – act cycle of closed loop motor control

P6. Power Law of Practice: the time to perform a task, Tn , on the nth trial follow a power law:

Tn = T1 n-= 0.4 [0.2~0.6]

P7. Uncertainty Principle. Decision time, T, increases with uncertainty about the judgement or decisions to be made

P8. Rationality Principle A person acts so as to attain his/her goals through rational action, given the structure of the task, information available, bounded by limitations of memory and processor ability

Goals + (Tasks + Inputs + Knowledge + Processor) limits -> Behavior

P9. Problem Space Principle. The rational activity in which people engage to solve a problem can be described in terms of

  1. A set of states of knowledge
  2. Operators for changing one state into another
  3. Constraints on applying operators
  4. The control of knowledge for deciding what operator to apply next

10/12/18 Psy/Orf 322 Human –Machine Interactions Spring 2004 Page 1