Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Millisecond thanks Dr. Fillmore for ample assistance and generously sharing the original stimuli!
Created: January 28, 2015
Last Modified: January 09, 2023 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements a dotprobe procedure to measure attentional bias with images. The implemented procedure is based on:
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.
Note: Due to the fact that no differences were found with complex stimuli, this script only implements the dot probe task with simple pictures.
4 minutes
After presentation of a fixation cross in the center of the screen, participants are presented with 2 pictures from two categories (here: alcohol and neutral pictures). The position of the pictures is randomly chosen to be either left or right to the location of the fixation cross. After a short duration, the two pictures disappear and a probe stimulus (here: X) appears in the location of one of the pictures. Participants are asked to press one key if the probe is left and another if the probe is right. Attentional Bias Measures (AB) are provided for alcohol and neutral (control) stimuli.
2 categories tested (Alcohol: alcohol; Filler: filler); within-design
- 1 block of 10 practice trials
- 1 block of 80 trials: 40 Alcohol trials (alcohol-neutral pairings) and 40 Filler (filler1-filler2 pairings)
10 alcohol/neutral simple pictures, all pictures presented 4 times
=> right/left, followed by prime/not followed by prime => 10 * 4 = 40 trials
- Filler Trials: same for filler trials
all 80 trials are randomly sampled without replacement
DEFAULT TRIAL SEQUENCES
fixation cross (500ms) -> target image pair (1000ms) -> tp_isi (0ms)-> probe (max. 1000ms) (latency measured from onset of probe until response or offset of probe; whichever comes first)
Stimuli were generously shared by Dr. Fillmore and can be easily edited under EDITABLE STIMULI
Original Instructions were generously shared by Dr. Fillmore.
They have been slightly edited by Millisecond.
They can be edited under section Editable Instructions.
File Name: alcoholdotprobe_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 |
| propCorrect | Proportion correct overall |
| meanRT | Overall mean latency (in ms) |
| propCorrectCongruentAlcohol | Proportion correct in congruent Alcohol trials |
| meanrtCongruentAlcohol | Mean latency of congruent Alcohol trials |
| propCorrectIncongruentAlcohol | Proportion correct in incongruent Alcohol trials |
| meanrtIncongruentAlcohol | Mean latency of incongruent Alcohol trials |
| abAlcohol | Attentional Bias for Alcohol pics : If AB_Alcohol > 0 => faster mean latencies to congruent alcohol trials than incongruent ones |
| propCorrectCongruentFiller | Proportion correct in congruent Filler trials |
| meanrtCongruentFiller | Mean latency of congruent Filler trials |
| propCorrectIncongruentFiller | Proportion correct in incongruent Filler trials |
| meanrtIncongruentFiller | Mean latency of incongruent Filler trials |
| abFiller | Attentional Bias for FillerA pics ('targets'): If AB_Filler > 0 => faster mean latencies to congruent FillerA trials than incongruent ones |
File Name: alcoholdotprobe_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, group, | With the current subject/groupnumber |
| 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 |
| task | 1 = practice; 2 = test |
| category | 1 = Alcohol ; 2 = Filler |
| congruence | 1 = probe and target (e.g. alcohol) position same; 2 = probe and target (e.g. alcohol) position different |
| targetPosition | 1 = target (e.g. alcohol) image on left; 2 = target (e.g. alcohol) image on right |
| compX-probeX | The x-coordinate (in %) of the target (e.g. alcohol)/ comp ('paired with target') /probe stims |
| itemNumber | Itemnumber of currently selected picture |
| targetImage | Stores the currently presented target (e.g. alcohol) image |
| compImage | Stores the currently presented comp ('paired with target') image |
| response | The participant's response (scancode of response button) 49 = N (left key) 50 = M (right 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 |
|---|---|---|
| readyDuration | The duration (in ms) of the get-ready-trial | 3000ms |
| fixationDuration:/targetduration | The duration of the fixation cross /the targets (default: 1000ms) | 500ms |
| tpIsi | Target-probe interstimulus interval in ms | 0ms |
| 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 | 1000ms |
| iti | Intertrialpause in ms | 0ms |
| probe | The symbol used for the probe | X |
| responseKeyLeft | The left response button | "N" |
| responseKeyRight | The right response button | "M" |
| minimumLatency | The minimum latency of a correct response that is included into summary variables (default: 100ms) | |
Physical Settings Of Display: Change The Settings To Optimize The Display On Your Computer Screen |
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| targetLeftX-targetRight | The x-coordinate in % of the right/left target | 27%, 73% |
| targetY | The y-coordinate of the target | center at 50% |
| fixationCrossHeight | The height of the fixation cross in canvas height percentage | 5% |
| probeHeight | The height of the probe in canvas height percentage | 5% |
| imageHeight | The height of the image in canvas height percentage | 40% |