Principles of Feedback Control Mafuyu Kitahara English Theme8 2006-05-08 Summary of Chapter 2, Carver & Scheier (1998), On the Self-Regulation of Behavior, Cambridge Univ. Press.

Feedback control Goal of Chapter 2 To show abstract princples Examples from domains other than psychology Feedback process Control of regulation of values within a system Cybernetics: coined by Wiener (1948) Background First computer in history: ENIAC (1946) Information science: bit, entropy, noise Systems without internal control: e.g., clock, camera

Negative feedback (1) Concept 4 elements: input, reference, comparator, output

Negative feedback (2) Example: thermostat Effect on evironment? Output has indirect connection with input

Additional issues (1) Sloppy vs. Tight control Lag Time how precisely the comparator works Thermostat: 0.01, 0.1, or 1 degree deviation? Lag Time Output function cannot work immediately Thermostat: Slow heater (steam) vs. Quick heater (gas)

Additional issues (2) Intermittent feedback Discontinuous: Continuous: Output side: heater is only ON or OFF Input side: sensor works occasionally Continuous: Automatic steering system in a ship

Further constructs (1) Positive feedback loops Thermostat example: set goal as more than 20C (needs upper limit)

Further constructs (2) Open loop systems No checking on the consequences e.g. Spark plugs in a car engine Order: prespecified Timing: depends on the speed Useful for high-speed control Precise, No lag time, No intermittency Not useful for psychology

Feedforward Anticipatory output First cycle Best estimate No input is available

Interdependency Interaction between feedback loops Not explicitly connected but disturbing each other

Reference value and input function Slow adjustment of reference value e.g. Sleep hours

Hierarchies Superordinate and subordinate systems e.g., person and thermostat