Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 05, 2015
Last Modified: January 11, 2026 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements a dotprobe procedure to measure attentional bias with word stimuli. The implemented procedure is based onon Miller and Fillmore (2010).
Note: this dot probe runs with words instead of images and the stimuli are presented on top and bottom of the fixation cross (instead of to the left and right)
Miller, M.A. & Fillmore, M.T (2010). The effect of image complexity on attentional bias towards alcohol-related images in adult drinkers. Addiction, 105, 883–890.
4 minutes
After presentation of a fixation cross in the center of the screen, participants are presented with 2 words. The position of the words is randomly chosen to be either bottom or top to the location of the fixation cross. After a short duration, the two words disappear and a probe stimulus (here: X) appears in the location of one of the texts. Participants are asked to press one key if the probe is on the bottom and another if the probe is on top.
2 categories tested; within-design
- 1 block of 10 practice trials
- 1 block of 80 trials: 40 category1 trials (category1target-category2comp pairings) and 40 category2 pairings
10 word pairs, all texts presented 4 times
category1:
=> top/bottom, followed by prime/not followed by prime => 10 * 4 = 40 trials
category2: the same
all 80 trials are randomly sampled without replacement
DEFAULT TRIAL SEQUENCES
fixation cross (500ms) -> target word pair (1000ms) -> tpIsi (0ms) -> probe (max. 1000ms) (latency measured from onset of probe until response or offset of probe; whichever comes first)
generic text stimuli - insert your own under section Editable Stimuli
stimuli are presented in white on a black background
Original Instructions were generously shared by Dr. Fillmore.
They have been slightly edited by Millisecond.
They can be edited under section Editable Instructions.
go to section INSTRUCTIONS HOW TO ADD ADDITIONAL CATEGORIES
File Name: genericdotprobe_words_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| 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 |
All Latency/Accuracy Summary Variables Are Based On Correct Responses With Latencies >= Parameters.Minimum_Latency (Default: 100Ms) |
|
| propCorrect | Proportion correct overall |
| meanRT | Overall mean latency (in ms) |
| propCorrectCongruentCategory1 | Proportion correct in congruent Category1 trials |
| meanrtCongruentCategory1 | Mean latency of congruent Category1 trials |
| propCorrectIncongruentCategory1 | Proportion correct in incongruent Category1 trials |
| meanrtIncongruentCategory1 | Mean latency of incongruent Category1 trials |
| abCategory1 | Attentional Bias for Category1 words : If AB_Category1 > 0 => faster mean latencies to congruent Category1 trials than incongruent ones |
| propCorrectCongruentCategory2 | Proportion correct in congruent Category2 trials |
| meanrtCongruentCategory2 | Mean latency of congruent Category2 trials |
| propCorrectIncongruentCategory2 | Proportion correct in incongruent Category2 trials |
| meanrtIncongruentCategory2 | Mean latency of incongruent Category2 trials |
| abCategory2 | Attentional Bias for Category2 words ('targets'): If AB_Category2 > 0 => faster mean latencies to congruent Category2 trials than incongruent ones |
File Name: genericdotprobe_words_raw*.iqdat
| Name | Description |
|---|---|
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| blockcode | The name the current block (built-in Inquisit variable) |
| blocknum | The number of the current block (built-in Inquisit variable) |
| trialcode | The name of the currently recorded trial (built-in Inquisit variable) |
| trialnum | The number of the currently recorded trial (built-in Inquisit variable) trialnum is a built-in Inquisit variable; it counts all trials run even those that do not store data to the data file. |
| task | 1 = practice; 2 = test |
| category | 1 = category1 ; 2 = category2 |
| congruence | 1 = probe and target (e.g. category1) position same; 2 = probe and target (e.g. category1) position different |
| targetPosition | 1 = target (e.g. category1) word on left; 2 = target (e.g. category1) word on right |
| compX-probeX | The x-coordinate (in %) of the target (e.g. category1)/ comp ('paired with target') /probe stims |
| itemNumber | Itemnumber of currently selected word |
| targetWord | Stores the currently presented target (e.g. category1) word |
| compWord | Stores the currently presented comp ('paired with target') word |
| response | The participant's response (scancode of response button) 49 = N (left key) 50 = M (right key) |
| responseText | Label of response key |
| latency | The response latency in ms (measured from onset of probe) |
| correct | Accuracy of response (regardless of whether latency >= parameters.minimum_latency) 1 = correct; 0 = incorrect |
| valid | Latency in ms that is >= parameters.minimum_latency |
| validCorrect | 1 = response was correct AND latency was >= parameters.minimum_latency; 0 = otherwise |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Design |
||
| probe | The symbol used for the probe | "X" |
Sizing/Location Parameters |
||
| targetTopY | The y-coordinate in % of the top target | 35% |
| targetBottomY | The y-coordinate in % of the bottom target | 65% |
| targetX | The x-coordinate of the target (center at 50%) | 50% |
| fixationCrossHeight | The height of the fixation cross in canvas height percentage | 5% |
| probeHeight | The height of the probe in canvas height percentage | 5% |
| wordHeight | The height of the words in canvas height percentage | 5% |
Timing Parameters |
||
| readyDuration | The duration (in ms) of the get-ready-trial | 3000 |
| fixationDuration | The duration of the fixation cross | 500 |
| targetDuration | The duration of the targets | 1000 |
| tpIsi | Target-probe interstimulus interval in ms | 0 |
| probeDuration | The duration of the probe presentation by default this scripts allows for responses for the entire probe duration the trial terminates after parameters.probeduration is over | 1000 |
| iti | Intertrialpause in ms | 0 |
| minimumLatency | The minimum latency of a correct response that is included into summary variables | 100 |
Response Keys |
||
| responseKeyTop | The top response button (left on QWERTY keyboard) | "T" |
| responseKeyBottom | The bottom response button (right on QWERTY keyboard) | "B" |