Description
In the web presentation, the Cross-Sections test was introduced to twins as an activity called "Laying the Foundation", with the following text: "It is here that the ancient scrolls tell us the castle needs to be built. It might not seem impressive now, but with your help we will build towers tall enough to scrape the sky! Your first task is to lay the foundation of our future castle by going through the plans presented to you and carefully choosing the correct ones. Will you accept the challenge?" This text was accompanied by the image below:
The test itself consisted of a practice item followed by 15 scored test items. Each item consisted of a stimulus image and 5 response images labelled A, B, C, D and E. The stimulus image represented a 3-dimensional, symmetrical geometric object intersected by a plane. Twins were asked to select the response image that best represented the 2-dimensional cross-sectional shape that would result from this intersection. Twins responded by clicking on one of the five response images. On clicking one of the images, the response was immediately submitted to the web server, and the next item was presented. A full table of test items, including stimulus and response images, can be found below under the heading Table of Test Items.
The test was preceded by an instructions page, which is reproduced here, and
which illustrates the nature of the test items:
The instructions page was followed by a single practice item. The practice item was optional: a twin could skip the practice item, attempt it once, or attempt it many times if they wished. On each attempt of the practice item, the twin was presented with feedback to say whether they chose the correct response, and what the correct response should have been. No such feedback was given after the main test items. No data for the practice item is included in the dataset.
The 15 main test items (subject to a discontinue rule) followed immediately after the practice item. The items were presented in numerical item number order, without any branching. Each item had a 20 second time limit, and a count-down timer was shown at the top-left corner of the page for every item, as a reminder of this.
Twins were encouraged to complete the test in one session if possible. Hence, no "come back later" button was placed on screen at any stage. However, it was possible to halt a test, by closing the browser or turning off the computer. After halting the test, it was possible for a twin to resume at a later time or date by logging in again: they would be presented with the next item to be attempted.
An individual test item could be compromised by an interruption after the item had started and before it had ended. Interruptions might result from twin actions such as closing the browser, or clicking the browser's back or refresh buttons. Interruptions might also be caused by random events such as computer crash or loss of internet connection. Such events seem to have been rare. The effect of interruption was to forfeit the item with zero score. On logging in at a later time after an interrupted item, a twin would be presented with the following item of the test.
Web Test Rules
- Scoring
For each of the 15 items, the correct response is given a score of 1, and any of the four incorrect responses is given a score of 0. The practice item does not contribute to the scoring. The maximum total score for the test is 15. - Discontinue rule
Discontinue the test after incorrect responses (scoring zero) in any four consecutive items. This rule applies from item 1 onwards; it is therefore possible to discontinue the test after item 4 at the earliest. - Timeout rule
A timeout of 20 seconds applies to each item. After 20 seconds with no response, the item is forfeited with zero score, and a "next item" screen appears. It was possible to pause indefinitely on the "next item" screen before resuming at the next item in the test.
Dataset Item Variables
The item variables relating to this test, as listed in the table below, were generated automatically by programs on the web server. For the sake of completeness, the table also lists derived variables relating directly to this test (rckcsdata1/2, rckcsstat1/2, rckcstime1/2, rckcstmn1/2). Note that the dataset only includes data for completed tests. If a twin started the test but left it unfinished, then the data for that test were deleted from the dataset.
Note that the item response variables have been recoded where appropriate with values -1, -2 and -4 to denote item timeout, discontinued or interrupted respectively. See the web data cleaning page for further details. The start and end dates/times have not been retained in the dataset.
| Variables | Explanation | Values |
|---|---|---|
| rckcsdata1/2 | Data flag: are test data present? [DERIVED VARIABLE] | 0=no, 1=yes |
| rckcsstat1/2 | Test status: was the test completed? [DERIVED VARIABLE] | 0=not started, 1=started but not finished, 2=finished successfully, 3=compromised by loss of data, 4=compromised by random responses |
| rckcssttm1/2 | Start date and time of the test [not in dataset] | Date-time values |
| rckcsentm1/2 | End date and time of the test [not in dataset] | Date-time values |
| rckcstime1/2 | Time interval from start to end of the test [DERIVED VARIABLE] | Minutes (decimal values) |
| rckcstmn1/2 | Mean item response time [DERIVED VARIABLE] | Seconds (decimal values) |
| rckcsXXan1/2 | Test item response for item XX* | 1=A, 2=B, 3=C, 4=D, 5=E (denoting the image selected), -1=timed out, -2=discontinued, -4=item interrupted |
| rckcsXXsc1/2 | Test item score for item XX* | 0=incorrect, 1=correct |
| rckcsXXrt1/2 | Test item response time for item XX* | Milliseconds (integer values) |
| rckcstot1/2 | Test total score: total score for all 15 items | 0 to 15 (integer values) |
| rckcstotp1/2 | Test total score expressed as a percentage | 0 to 100 (decimal values) |
* XX denotes the item number, 01 to 15
Table of Test Items
The test items are tabulated below, for the practice item and the 15 main test items. In each case, the item number, correct response (A-E), stimulus image and five response images (A-E) are shown.
practice item: correct response is C
item 1: correct response is D
item 2: correct response is B
item 3: correct response is A
item 4: correct response is D
item 5: correct response is C
item 6: correct response is C
item 7: correct response is A
item 8: correct response is C
item 9: correct response is E
item 10: correct response is B
item 11: correct response is B
item 12: correct response is B
item 13: correct response is E
item 14: correct response is B
item 15: correct response is D
