TEDS Data Dictionary

The 10 Year Picture Completion Web Test

Contents of this page:

Introduction

This page describes the Picture Completion test that was included in the 10 Year twin web study battery.

Description of Test

The test consists of a series of pictures of recognisable objects or scenes, each with an essential detail omitted from the picture. (The pictures are shown in a table below.) The twin is asked to click on the relevant part of the picture on screen, to identify the part that is missing. There is a time limit of 20 seconds for each picture (shown pictorially by a moving time bar on screen). If 20 seconds passes before the twin has clicked on the picture, this is treated as an incorrect response (zero score), and then the twin is shown a prompt asking them to continue with the next picture.

In order to determine whether a given click corresponds to a correct or an incorrect response, each picture is divided into a rectangular grid. Each cell of the grid is numbered. When a twin clicks on the picture, the relevant grid number is recorded as the item response. The grid is depicted in the table of items below; the correct grid number(s) for each item are also shown in the table.

There are 30 main picture items, plus one initial 'practice' item which contributes to the branching but not to the test score. A twin taking the test may be presented with fewer than 30 items, because of the branching and discontinue rules, which are described below.

Test Rules

  • Scoring
    For each question, a correct response is given a score of 1, and an incorrect response is given a score of 0. Correct and incorrect responses are based on grid numbers corresponding to where each picture was clicked (see table of items below). The maximum total score for the test is 30 (not including the practice item).
  • Branching rules
    • Start with the practice item p1, and proceed to item 5.
    • If both the practice item and item 5 are correct, give credit for items 1-4 (as though they had been answered correctly, gaining a score of 1 for each item), then proceed upwards from item 6.
    • If either the practice item or item 5 is incorrect (scoring 0), attempt the lower items (1-4) in reverse order. Then:
      • If any two successive items are correct (e.g. 4 and 3), then give credit for any of items 1-4 not yet attempted; then proceed upwards from item 6. Note that if either the practice item or item 5 is correct, while the other is incorrect, and this is followed by a correct answer for item 4, then this results in an upward branch to item 6 (the practice item and item 4 are treated as successive items for this rule, as are item 5 and item 4).
      • If no two successive items are correct, the test ends after item 1 has been attempted.
  • Discontinue rules
    Discontinue the test after five scores of zero in any five consecutive items. This rule applied throughout the test after five or more items had been attempted.
  • 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. On resuming the test, the twin is taken to the next item in sequence as described above.

Item Variables

The item variables relating to the Picture Completion test, as listed in the table below, were generated automatically by programs on the web server during the course of the test. Note that the dataset only includes data for completed tests. If a twin started the test but left it unfinished, then the data for the test were not used.

In most cases the values of these variables have been left unaltered, although some have been recoded during data cleaning as follows. See the web data cleaning page for further details.

  • For timed out items, the item response variable is recoded from missing to -1, and the item answer time is recoded from 20 to missing (item scores are 0)
  • For items skipped due to the discontinue rule, the item response variable is recoded from missing to -2, and the item score is recoded from missing to 0.
  • For items skipped and credited due to upward branching, the item response variable is recoded from missing to -3 (the item score is already recorded as 1 on the web server).
  • For items that crashed or malfunctioned in any way, the item response variable is recoded from missing to -4, and the item score is recoded from missing to 0.
  • For twins identified as random responders in this test, the status flag is recoded from 2 to 4, the data flag is recoded from 1 to 0, and all item variables are recoded to missing (test data deleted)

The test start and end dates and times, and item answer and download times, and item orders, have not been retained in the dataset.

VariablesExplanationValues
jpcstat1/2 Test status: outcome of test 0=not started, 1=started but not finished, 2=successfully completed, 4=random responses
jpcdata1/2 Data flag: is test data present in the dataset? 0=no, 1=yes
jpcstdt1/2 Start date of the test [not in dataset] Date values
jpcsttm1/2 Start time of the test [not in dataset] Time values
jpcendd1/2 End date of the test [not in dataset] Date values
jpcendt1/2 End time of the test [not in dataset] Time values
jpcsess1/2 Number of sessions (at the computer) used by the twin to complete the test. Integer values of 1 or above
jpctime1/2 Time taken to complete the test, in seconds Integer values (number of seconds)
jpc01a1/2 through to jpc30a1/2
(items 1-30),
and jpcp1a1/2 (practice item)
Item response (see table of items below for details) Integer, representing the number of the grid square clicked.
Alternatively, -1=timed out, -2=discontinued, -3=credited due to upward branching, -4=item crashed.
jpc01s1/2 through to jpc30s1/2
(items 1-30),
and jpcp1s1/2 (practice item)
Item score (see table of items below for details) 0=incorrect, 1=correct
jpc01at1/2 through to jpc30at1/2
(items 1-30),
and jpcp1at1/2 (practice item)
Answer time: length of time (in seconds) taken by the twin to respond to this item [not in dataset] Integer values (number of seconds)
jpc01dt1/2 through to jpc30dt1/2
(items 1-30),
and jpcp1dt1/2 (practice item)
Download time: length of time (in seconds) between the end of the previous item and the start of this item; time needed to download files for this item [not in dataset] Integer values (number of seconds)
jpc01o1/2 through to jpc30o1/2
(items 1-30),
and jpcp1o1/2 (practice item)
Order or sequence of this item in the test; dependent on the branching path taken by the twin through this test [not in dataset] Integer values of 1 or above

Test Items

The numbering of the items, shown in the table below, equates to the numbering used in the item variables. Note that this is not the same as the order in which items were presented to twins in the test (see branching rules above).

itempicturecorrect response (missing part) correct grid number(s)
(grid)Picture Completion test grid (the picture is for item 4, but this same grid was used for all items) (numbers below, in this column, refer to this grid)
p1 (practice item)Picture Completion test item p1 lead tip of pencil 73, 74
1Picture Completion test item 1 ear of fox 27-29, 40
2Picture Completion test item 2 lid flap of box14-18, 26-30, 38-42, 50-54, 62-66
3Picture Completion test item 3 whiskers on one side of cat's face31, 32
4Picture Completion test item 4 finger nail of little finger32
5Picture Completion test item 5 leg of elephant75-77, 87-89, 99-101
6Picture Completion test item 6 strap of watch92
7Picture Completion test item 7 bottom door hinge52, 64, 76, 88, 100
8Picture Completion test item 8 reflection of doll in girl's hand40, 52, 64
9Picture Completion test item 9 number 11 on face of clock29
10Picture Completion test item 10 handle on second drawer from top44, 45
11Picture Completion test item 11 holes in belt61-62, 73-74, 86-91
12Picture Completion test item 12 veins in part of the top leaf16-17, 27-29
13Picture Completion test item 13 second-bottom step56, 66-69, 78-79
14Picture Completion test item 14 eye lashes on one eye55, 56
15Picture Completion test item 15 dot on top of right-hand die (there should be 6 dots)33
16Picture Completion test item 16 plug hole in bath52-55, 64-66
17Picture Completion test item 17 filament of bulb30-32, 42-44, 54-56, 66-68
18Picture Completion test item 18 hole in top of whistle40-42, 52-56, 67-68
19Picture Completion test item 19 black keys on piano keyboard63-70
20Picture Completion test item 20 hinge where scissor blades meet66-68
21Picture Completion test item 21 eye brow40-42, 53
22Picture Completion test item 22 red liquid in thermometer bulb103
23Picture Completion test item 23 slat near top-left of lattice7, 17-19, 29-30, 39-41, 50-52, 62-63, 73-74
24Picture Completion test item 24 pith dividing segments in part of orange43-45, 55-57
25Picture Completion test item 25 gill of fish52-53, 64-65
26Picture Completion test item 26 labels on cans, on top-right shelf45-48
27Picture Completion test item 27 cable attached to phone hand set (on either side)50-52, 57-58, 62-64, 69-70, 75-76, 81-82
28Picture Completion test item 28 spoke of umbrella30, 43, 55-56, 67-68
29Picture Completion test item 29 shadow of tree62-64, 73-77, 86-88
30Picture Completion test item 30 eye hole for lace of shoe42