Assignment #2

SI 688

Fall 2010

Student ID:

NOTE:

1.  Do NOT put your name or uniqname on this document anywhere or in the file name.

2.  Please name your file thus: <studentid>-assn2.doc (or .docx, or .pdf). For example, if your student ID is 12345678, your submission file name would be 12345678-assn2.doc.

Answers should be brief. Most questions can be answered in 1-2 paragraphs. None should require more than one full page. Cite your references using the APA style. Any web pages you visit as part of answering these questions should be formally referenced if you end up using information from them.

Please enter your responses in this document and turn your document in via the CTools assignments tool. Any papers that do NOT include your student ID on this first page and in the filename will be returned for revision, as will any papers that DO include your name or any identifying information other than ID.

Question 1

For each of the following examples, describe someone for whom the chosen control would serve as an affordance and someone for whom it would not. Explain why in both cases.

In your answers, please be sure to demonstrate the following:

·  That you know what an affordance is

·  That you can name at least two types of reasons why something could be an affordance for one person and not for another person.

1a) A door knob.

1b) An underlined, blue word on a web page.

1c) A shaded, slightly raised button on a dialog box with the word “Cancel” written on it.

1d) The characters “$_” printed in white at the top left corner of an all-black screen.

1e) An picture of a trashcan in the lower right corner of a screen containing a lot of other, similar-sized icons.

Question 2

Watch the Apple “Knowledge Navigator” video:

http://www.youtube.com/watch?v=kl3CVaWtF-o&feature=related

Name two metaphors that the system implements to try to facilitate the user’s interaction with the system. Explain the schema(s) that are invoked by the metaphors and give an example from the video of how that schema helps the user know how to operate the system.

Be sure to demonstrate your understanding of what a schema is and how metaphors and schema are related to each other.

Question 3a

For each of the lists below, describe how you would estimate the length of time it would take to select an item. In particular, state whether the Hick-Hyman Law would provide a suitable estimate and, if so, provide the estimate[1]. For List #1, assume the user needs to select “Detroit” as a travel destination. For List #2, assume the user wishes to purchase a radar detector and wishes to see the price on one.

List #1 / List #2
Austin / wanted ti-84 plus calculator
Baltimore / iPod Mini 2nd Gen 4GB (silver) w/ iPod Dock
Boston / ALPINE TYPE-R 12' 600RMS 1800WATTMP
Charlotte / Sony 51" WIDESCREEN TV - BIG SCREEN HDTV
Chicago / sony bloggie mhs-pm5
Columbus / 2 mtx 12" subs with amp and box must sell today
Dallas / Kenwood 2 10's Good Condition!
Denver / WTB pci wifi cards
Detroit / Xbox 360 Wireless Adaptor
El Paso / 14" Magnavox TV
Fort Worth / DJ - Speakers
Houston / Toshiba - 37" LCD 1080p
Indianapolis / 16GB 3rd Gen. New with Warranty iPod Touch
Jacksonville / STEREO SPEAKERS
Las Vegas / BRAND NEW RADAR DETECTOR.
Los Angeles / 2010 TOPPS UPDATE ICHIRO ALL-STAR JERSEY MARINERS
Louisville / NEW BROTHER INTELLIFAX-1270e PLAIN PAPER FAX MACHINE
Memphis / 26 inch LCD TV!
Milwaukee / LCD TV WESTINGHOUSE FLAT SCREEN 1080 DPI
Nashville / Do you need Projection Tv Repair?
New York / Memorex DVD/CD Player
Philadelphia / NIKON CAMERA, LENS AND BAG
Phoenix / 2 10
Portland / XBOX 360 & PS3 REPAIRS (RROD, YLOD, DISC WONT READ)
San Antonio / Ipod nano camera 8gb green
San Diego / (2) Audiobahn 12'' 4400watt!!
San Francisco / B&K/Epos stereo system
San Jose / 32gb Ipod touch 3g
Seattle / PS ONE
Washington

Question 3b

A user interface you are desgning needs to present the user with a list of 64 countries from which to choose. Use the Hick-Hyman Law to determine whether it would it be more efficient to display this as a single list of 64 items or 8 lists of 8 items with the top level list showing the alphabetical range of each sublist (e.g., A-C, D-F,…) and the second-level list showing the country names themselves.

Assume the following:

·  Users will be looking for a specific country and will not need to think about what it is.

·  They will not require any “mental time” to identify the alphabetical range of the country they’re looking for (e.g., if the country they are looking for is Belgium they will “instantly” identify A-C as the correct top level item).

·  You can ignore the time it would take to execute any necessary selections (e.g., clicking on a menu or country item).

·  No scrolling will be necessary.

Your answers to both 3a and 3b should demonstrate that you understand how and when to apply the Hick-Hyman Law. You should also demonstrate that you understand what other principles to apply to describe list selection in cases where Hick-Hyman does NOT apply.

Question 4

Laura and Lindsay have both been hired for a data entry position and will be required to learn a new system. Based on their cognitive abilities, sketch their relative learning curves and explain why the curves look different.

Your answer should demonstrate your understanding of the relationship between cognitive ability and skill acquisition.

Laura / Lindsay
Fluid Intelligence/Reasoning (Gf) / 90 / 65
Crystallized Intelligence/Knowledge (Gc) / 92 / 52
General (domain-specific) Knowledge (Gkn) / 88 / 48
Visual-Spatial Abilities (Gv) / 72 / 72
Auditory Processing (Ga) / 66 / 68
Short-term Memory (Gsm) / 78 / 76
Long-term Storage and Retrieval (Glr) / 72 / 73
Cognitive Processing Speed (Gs) / 75 / 75
Decision/Reaction Time or Speed (Gt) / 71 / 72
Psychomotor Speed (Gps) / 49 / 91
Quantitative Knowledge (Gq) / 91 / 60
Reading/Writing (Grw) / 93 / 68
Psychomotor Abilities (Gp) / 56 / 88
Olfactory Abilities (Go) / 72 / 89
Tactile Abilities (Gh) / 77 / 81
Kinesthetic Abilities (Gk) / 73 / 78

Question 5

There are two ways to insert a formula into a Goolgle Spreadsheet. One is to type the formula in directly, along with its arguments. Another is to select the formula from the “Insert | Formula” menu and then select the range for the parameters. Assume you wish to insert a formula to find the average of 10 numbers that have already been input into the spreadsheet. Use a KLM analysis to determine which method would be the most efficient for adding the formula.

Use the Keiras’ guidelines for applying mental operators, which can be found in the GOMS tutorial under CTools/Resources.

Your answer should demonstrate that you know how to apply the KLM to estimate the human performance of a system. You should clearly state any additional assumptions you need to make in order to answer this question.

Question 6

You are consulting on a project to design a new blog management system aimed at K-12 students. One of the software developers on the project has raised an issue with the current design that she believes needs to be fixed: if an author changes their “signature” it will only apply to future blog posts—it will not be retroactively applied to posts that were made in the past. She is proposing a change to the design that would force the “signature” to apply to all posts. Moreover, she is arguing that the signature editor should be changed to allow users to include several “macros” in their signatures including the current date, current time, geographical location of the author, total number of posts the author has made up to that point, PageRank of the author’s site, and several other computed values.

Describe the design dilemma being presented by the developer in terms of the Cognitive Dimensions Framework to help clarify the discussion. You do not need to provide a recommendation, your job is just to reformulate the discussion.

Your answer should demonstrate that you understand several cognitive dimensions, that you know how to apply them to the analysis of an interactive system, and that you understand how to use them to describe design tradeoffs.

Question 7

Drawing on your understanding of human cognition, explain why the cognitive dimension of consistency is important in interactive systems.

Your answer should demonstrate that you understand the cognitive foundations for this particular cognitive dimension, and should draw on readings from earlier in the course.

[1] If applying the Hick-Hyman Law, use the formulation provided in the Week 5 slides and use a=300 and b=200.