Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 13, 2013
Last Modified: January 20, 2025 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements the change blindness paradigm as described in:
Beck, M.R. & Levin, D.T (2003). The role of representational volatility in recognizing pre- and postChange objects. Perception & Psychophysics, 65, 458-468.
15 - 20 minutes
Participants are presented a 'before' and an 'after' picture for 2s. Each picture consists of 3-16 different objects that are arranged in a 4x4 matrix. One object is changed from the 'before' to the 'after' picture. In two recognition tasks participants are asked to select a) the preChange object and b) the postChange objects out of 4 possible choices. The order of the tasks is counterbalanced between participants.
• 'before' and 'after' picture: consist of 3-16 objects, randomly arranged in a 4x4 matrix
('after' picture is slightly shifted to the left or right by default)
=> one object changes from the 'before' to the 'after' picture
• order of recognition tasks (preChange picture -> postChange picture) is counterbalanced by groupnumber
• recognition tasks present: one foil (a different one for each task), the target item
(preChange object or postChange object, 2 unrelated objects (different ones for each task);
the order of the objects is randomly determined
• by default half the 'after' pictures are shifted to the left, the other half to the 'right'
(randomly determined)
• Test Block: 14 different array objects (3-16) * 4 repetitions = 56 trial sequences
•optional practice block: 10 practice trials with number of array objects = 4 and with error feedback
(it is run by default);
array presentation times can be set independently from testing session under section Editable Parameters.
The images provided with this script are digitalized versions (300px x 300px) of the pictures presented by:
Snodgrass, J. G., & Vanderwart, M. (1980). A standardized set of 260 pictures: Norms for name agreement,
image agreement, familiarity, and visual complexity. Journal of Experimental Psychology:
Human Learning & Memory, 6, 174-215.
The images were created in Paint.NET by Millisecond.
not original; can be edited under section EDITABLE INSTRUCTIONS
File Name: changeblindness_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| startDate | Date the session was run |
| startTime | Time the session was run |
| subjectId | Participant ID |
| groupId | Group number |
| sessionId | Session number |
| elapsedTime | Session duration in ms |
| completed | 0 = Test was not completed 1 = Test was completed |
| expCondition | 1 = preChange Forced Choice Task before postChange Forced Choice Task 2 = postChange Forced Choice Task before preChange Forced Choice Task |
| practiceArrayPresentationTime | Sets the object array presentation time during practice (default: 3000ms) a practice session wasn't mentioned in the original article |
| testArrayPresentationTime | Sets the object array presentation time during testing (default: 2000ms) could also be declared as a list in case different test_arraypresentationtimes = IV |
| arrayISI | (interstimulus) time between offset of 'before' array and onset of 'after' array (default: 350ms) in ms |
| tr4AFCISI | Time between the two recognition tasks (default: 500ms) in ms |
| iti | (intertrial) time between end of 2nd recognition task and onset of next 'before' array (default: 1000ms) in ms preChange3Hits- |
| postChange3Fass | Sums up hits/False Alarms (FAs) for preChange and postChange recognition |
| preChange3Diff | Difference in values.preChange_hits - values.preChange_FAs for array number = 3 (same for all array numbers) |
| postChange3Diff | Difference in values.postChange_hits - values.postChange_FAs for array number = 3 (same for all array numbers) the same for all array numbers 3-16 |
File Name: changeblindness_raw*.iqdat
| Name | Description |
|---|---|
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| blockCode | Name of the current block |
| blockNum | Number of the current block |
| trialCode | Name of the current trial |
| trialNum | Number of the current trial |
| expCondition | 1 = preChange Forced Choice Task before postChange Forced Choice Task 2 = postChange Forced Choice Task before preChange Forced Choice Task |
| trialCounter | Tracks the number of trials per block |
| shift | 1 = right shift of coordinates for postChange presentation 2 = left shift of coordinates for postChange presentation |
| numberofObjects | Stores the current number of objects in the array |
| arrayPresentationTime | Current arraypresentation time |
| stimulusItems | The presented stimuli in order of trial presentation |
| response | The participant's response (scancode of response buttons) |
| correct | Accuracy of response: 1 = correct response; 0 = otherwise |
| latency | The response latency (in ms); measured from: onset of trial |
| arrayItemNumbers | String variable that stores all the itemnumbers of the selected array objects |
| preChangeObject | Contains the itemnumber of the preChanged object (= same as object1) |
| postChangeObject | Contains the itemnumber of the postChanged object |
| preFoilObject | Contains the itemnumber of the prefoil object (= same as object2) in preChange lineup |
| postFoilObject | Contains the itemnumber of the postfoil object (= same as object3) in postChange lineup |
| preUnrelatedObject1 | Contains the itemnumber of a totally new object in preChange lineup |
| postUnrelatedObject1 | Contains the itemnumber of a totally new object in postChange lineup |
| preUnrelatedObject2 | Contains the itemnumber of a totally new object in preChange lineup |
| postUnrelatedObject2 | Contains the itemnumber of a totally new object in postChange lineup object1- |
| object16 | Stores the itemnumber of object1 to object16 (screen locations randomly determined) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
| runPracticeBlock | True = runs a practice block (see block.practice under BLOCKS) - default option false = skips the practice block (!!!Instructions need to be updated accordingly) | |
| practiceArrayPresentationTime | Sets the object array presentation time during practice in ms a practice session wasn't mentioned in the original article | 3000ms |
| testArrayPresentationTime | Sets the object array presentation time during testing in ms could also be declared as a list in case different test_arraypresentationtimes = IV | 2000ms |
| arrayISI | (interstimulus) time in ms between offset of 'before' array and onset of 'after' array | 350ms |
| tr4AFCISI | Time between the two recognition tasks | 500ms |
| iti | (intertrial) time in ms between end of 2nd recognition task and onset of next 'before' array 4x4 Matrix Presentation | 1000ms |
| pictureHeight | Sets the picture size in canvas height percentages | |
| column1X: - | ||
| row4Y | Sets the picture center (in %) for the 4columns/4rows for 'before' picture | |
| shiftPercent | Determines how much the after picture should be shifted to right/left | 10% = 1/2 column width |