Human Factors Hmwk 2

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Assignment 2 – Human Cognition and Information Processing

Due: On Collab: January 12, 2013 by 8:00 AM, 50 possible points

1. Name and describe one attention phenomenon (2 points)

Selective attention: Only paying attention to desired stimuli, ignoring the rest Example: Cocktail party effects - Hearing your name in a noisy party (pop out effect)

2. Why should you avoid and when should you use ALL CAPS? (6 points)

It's harder to distinguish all caps versus lower case. Using all caps violates the repetition principle of small multiples since there is a lack of difference with cap letters (no shape coding) Furthermore, it takes up more space.

In isolated cases, ALL CAPS can be used for emphasis.

3. What is the proximity-compatibility principle for interface design? (2 points)

The Proximity principle states that conceptually related items should be in close proximity and conceptually unrelated items should be distant

4. Consider the task of using a calculator . (10 points) What would be an example of a:

a. "Gulf of Execution"?

A gulf of execution is a disparity between the user's intentions and allowable actions. User having trouble trying to evaluate a polynomial graphically, which requires a number of input steps in order for the calculator to produce a graph. If the user is not familiar with the process, the user may not be able to produce a graph.

b. "Gulf of Evaluation"?

A gulf of evaluation is not being able to tell if the user's action had the desired effect. For the calculator example, a user could input a long series of basic math operations (add/subtract), with the calculator only displaying the last product (no feedback to check if he/she input the correct functions - this is usually possible with a graphing calculator)

c.Skill-based behavior?

Skill based behavior involves a real-time signal, directly coupled to the environment. An example with a calculator is turning the calculator on or off by pressing the "on/off" button.

d.Rule-based behavior?

Rule-based behavior uses if-then rules to map between a familiar sign (usually perceptual cues) in the environment and the appropriate action. No formal reasoning is required. An example is converting degrees to radians using the standard formula, angle in radians = angle in degrees * π/ 180 - or any other simple formula.

e.Knowledge-based behavior?

Knowledge based behavior requires serial, analytical reasoning based on a mental model (internal, symbolic representation of the relevant constraints and relationships in the environment.). An example is finding and graphing the rate of acceleration given a set of speeds versus time, where the user has to apply multiple rules and processes to accomplish the task.

5. Topic of Human Memory

a.Name one benefit of chunking (2 points)

Chunking allows subject to hold more information in short term memory, since its generally limited to 7 bits +/-2 (although that has been contested by psychology - certain languages with long words (like German) have shown that the average amount of bits is closer to five.)

b.Name two limitations of/problems encountered with human long-term memory (3 points)

* Retrieving the information - we generally reconstruct information as needed, rather than recalling it exactly (faulty memory). * Only stores info we judge "important"

c.Name two limitations of/problems encountered with human short-term memory (3 pts)

* limited capacity (generally 7 bits +/- 2)
* Memory lost within 30 seconds unless repeated (rehearsed)

6. Topic of Vigilance and Workload

a.Describe the relationship between vigilance and mental workload with a diagram. (4 points)

Vigilance is a person's ability to maintain attention for the task at hand. This concept is usually a factor when the action requires monitoring some interface or area (i.e radar watch, factory inspection lines, etc.)....
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