Cognitive Elements of Menu Selection 조 성 식조 성 식

1/20 Contents Menu Selection Process Problem Solving & Search Strategies Cognitive Layouts of Mental Models Summary - Information Acquisition and Search - Choice Process and Time - Response Process - Evaluation and Error Detection - Heuristics - User Strategies and Styles - Menu Selection as a Metaphor - Schemata and Scripts - Cognitive Layouts of Menus

2/20 Menu Selection Process Information Acquisition and Search Choice Process and Time Evaluation and Error Detection Response Process -Information Processing Models -Models of Visual Search -Stopping Rules -Searching Time -The Number of Alternatives -The Difficulty of the Choice -Luce’s Choice Axiom

3/20 Information Acquisition and Search (1/5) Information Processing Models - The way in which a user scans a menu frame for information depends on the task and the user's prior knowledge about the frame. - Explicitly known target * The user engages in a visual matching process. * Menus which use visually and semantically distinct alternatives will result in faster response times and fewer error. - Partially specified target * The user engages an encoding and evaluation process. * subjective likelihood & subjective utility * optimizing rule & satisficing rule Menu Selection Process

4/20 Information Processing Models Menu Selection Process Information Acquisition and Search (2/5)

5/20 Models of Visual Search Menu Selection Process Information Acquisition and Search (3/5) Stopping Rules - Self-terminating Search - Exhaustive Search - Redundant Search

6/20 Searching Time - S = E(A)t + k + c where E(A) is an expected number of alternatives that will be inspected t is the time required to read one alternative k is the key-press time c is the computer response time - P(k) = 1 - (1 - p) k where p is the probability of finding the target on a single saccade k is the number of saccades required to find the target Menu Selection Process Information Acquisition and Search (4/5) - S = t / p where t is the time to be taken by a saccade - S = n t where p = 1/n, n is the number of alternatives

7/20 Searching Time Menu Selection Process Information Acquisition and Search (5/5) unpracticed Highly practiced

8/20 Choice Process and Time Menu Selection Process S = a + b log 2 (n) S = a - b log 2 (p i ) The number of Alternatives : Hick-Hyman Law Axiom 1 : p(a 1 | a 1, a 2 )/p(a 2 | a 1, a 2 ) = p(a 1 | a 1, a 2,..., a n )/p(a 2 | a 1, a 2,..., a n ) The Difficulty of the Choice Luce’s Choice Axiom Axiom 2 : p ij =0 then a i may be neglegible

9/20 Response Process Enter a code Menu Selection Process Pointing to the Alternative - Analogue pointing devices : Fitts’Law, R = a log 2 (d/w) + b - Discrete pointing using arrow keys : R = a (dx + dy) + b

10/20 Evaluation and Error Detection The feedback may be receipt of some information, the location of a target item, the execution of a function, or the presentation of subsequent menu frame. Consequently, feedback engages another decision making process in hierarchical menu search. How this affects the search strategy will be discussed in the next section. Menu Selection Process

11/20 Problem Solving & Search Strategies Heuristics - Generate-Test - Hill Climbing - Test-Operate-Test-Exit - Means-Ends Analysis User Strategies and Styles - Pathiness - Ringiness - Loopiness - Spikiness - NV/NT - NV/NS - Scanning - Browsing - Searching - Exploring - Wandering - Shallow and broad - Narrow and deep - Progressive deepening

12/20 Heuristics (1/2) Generate-Test Hill Climbing - Generate a candidate -> Test to see if it is actually a solution. Problem Solving & Search Strategies - 4 difficulties * difficult to generate candidates * hard to test see if it is actually a solution * a large number of candidates -> unlikely to work * the correct solution has a low probability of being selected - Problem reduction approach

13/20 Heuristics (2/2) Test-Operate-Test-Exit Means-Ends Analysis Goal –> subgoal –> sub-subgoal Problem Solving & Search Strategies Ex) Viewing file A –> find file A –> run directory program

14/20 User Strategies and Styles (1/2) Shallow and broad Problem Solving & Search Strategies Progressive deepening Narrow and deep - likely to survey a wide number of possible solutions but explore them only superficially. - appropriate for placing pieces in a jigsaw puzzle. - likely to limit his or her search to only a few alternatives and explore them in depth. - appropriate for solving the Tower of Hanoi puzzle or playing chess. - a mixture of upper two strategies - particularly useful when there are a fair number of possible solutions and it is not clear.

15/20 User Strategies and Styles (2/2) - Pathiness - Ringiness - Loopiness - Spikiness - NV/NT - NV/NS - Scanning - Browsing - Searching - Exploring - Wandering Canter, Rivers, Storrs (1985) Problem Solving & Search Strategies

16/20 Cognitive Layouts of Mental Models Menu Selection as a Metaphor Schemata and Scripts Cognitive Layouts of Menus

17/20 Menu Selection as a Metaphor Example : Restaurant menus  Computer menus Cognitive Layouts of Mental Models Metaphor a literary device is to transfer the reader's concrete knowledge about a familiar thing to an unfamiliar subject being written about. - Norman and Chin (1989) provide a comparison between restaurant menus and computer menus. - The restaurant menu generates a powerful metaphor for human/computer interaction.

18/20 Schemata and Scripts Schema - A diagrammatic outline of something that conveys its essential characteristics. Cognitive Layouts of Mental Models Script (called an event schema) - An expected or stereotypical sequence of actions and events. - Most information fits somewhere in between perfect conformity and total chaos.

19/20 Cognitive Layouts of Menus Road Map Tree Smorgasbord Cognitive Layouts of Mental Models

20/20 Summary The user must search for information, encode the meaning of alternatives, assess the alternatives, make a choice and effect a response. Good menu design takes into consideration such human factors to increase speed and reduce errors. Good user interface design should convey a sense of meaning and engage schemata that lend themselves to solutions of the tasks being performed.