Week 10-1: Selection of Action

1. 1 Week 10-1: Selection of Action This module will provide you with a general overview of the needs assessment process. Later modules will provide more detail on the steps involved. This module will provide you with a general overview of the needs assessment process. Later modules will provide more detail on the steps involved.

2. 2 Week 10 Topics Lecture 10-1 Types of Actions Simple Reaction Time Choice Reaction Time Hick-Hyman Law Lecture 10-2 Speed-Accuracy trade-offs Variables affecting Choice RT

3. Selection of Action Types of actions (Rasmussen, 1980, 1986) Skill-based: execution of highly-learned procedural memory�occurs largely outside of awareness Rule-based: execution of simple �if-then� rules�imposes some working memory load Knowledge-based: execution of actions based on extensive review of information in the environment and long-term memory � classical decision making 3 After Abbott and Costello High HT: very consistent stimulus-response mappings, but although information was conveyed (�back to third again�), misunderstandings perpetuated. Costello�s conceptual model of the team was inaccurate Why was the misunderstanding not corrected? Ineffective feedbackAfter Abbott and Costello High HT: very consistent stimulus-response mappings, but although information was conveyed (�back to third again�), misunderstandings perpetuated. Costello�s conceptual model of the team was inaccurate Why was the misunderstanding not corrected? Ineffective feedback

4. Modeling Simple Reaction Time Effects Effect of Stimulus Intensity Sensory evidence aggregated (integrated) over time Stimulus intensity affects rate of information aggregation 4

5. Variables Influencing Simple Reaction Time Temporal Uncertainty warning signals may precede imperative stimulus Warning Interval (WI): interval between warning signal and imperative stimulus Lowers criterion (top-down effect) Example: amber traffic light 5

6. Variables Influencing Simple Reaction Time Effect of Variations in Warning Interval (WI): WI short and constant (e.g., 0.5 s) Temporal uncertainty reduced or eliminated RTs shorten to nearly 0 WI long or variable Temporal uncertainty is increased Uncertainty in internal timing mechanism increases linearly with duration Simple RTs increase, reach maximum of 700ms 6

7. Variables Influencing Simple Reaction Time Expectancy Modeled as a criterion shift Faster RTs more false alarms If WI is varied within a block, expectancy increases for longer WIs EXAMPLE: Van Der Horst (1988) Vehicle controlled traffic lights Driver expects the light to remain green since he knows the light senses his vehicle RT to yellow light is delayed by a second! 7

8. Variables Influencing Choice Reaction Time Amount of information transmitted is important Choice RT requires operator to map stimulus to response -- information must be transmitted More complex decisions (requiring more information) require longer to initiate Information Theory: Three variables influence information conveyed by a stimulus Number of possible stimuli Probability of a stimulus Context or sequential constraints 8

9. Information & Choice Reaction Time Hick-Hyman Law Choice RT increases linearly with magnitude of stimulus information Hyman (1953) also varied the probability and sequential expectancy (context) of a stimulus Information theory: unequal probabilities reduce the average amount of stimulus information Mean RT for block of trials is shortened by this reduction of information accordingly, thus 9

10. Stimulus Frequency & Choice Reaction Time Fitts, Peterson, and Wolpe (1963) Examined RT to highly frequent and rare events Prediction of Hick-Hyman frequent events have little information, rare events have high information fast RT for frequent events, slow RT for rare events IMPORTANT IMPLICATION! RT for real world tends to take much longer than in lab studies Summala (1981) Time to break in response to a roadway obstacle is estimated to be 2-4 seconds Why? 10

11. Accuracy and Choice Reaction Time Speed-accuracy trade-off Tendency to make more errors as you try to respond faster Hick-Hyman: constant bandwidth for information transmission Constant bandwidth mean that if speeded response doesn�t allow for all information to be transmitted, then not enough information will be transmitted for accurate responses Human performance does not exactly follow the constant bandwidth assumption 11

12. Speed-Accuracy Operating Characteristic SAOC curve Similar to P(H) & P(FA) in SDT Analogous to the ROC curve in SDT Bias toward speed or accuracy is analogous to bias in SDT toward increasing hits or reducing FA 12

13. System design and the Speed-accuracy Tradeoff Certain design features seem to automatically shift performance along the SAOC Auditory presentation enhances speed emphasis Aircraft designers use auditory displays only for critical alerts that require quick responses Presentation of more information will tend to slow performance and increase accuracy Older adults tend to have an accuracy-emphasis Stress can induce a speed emphasis Some nuclear power regulations require operator to take no action for a period of time after a fault 13