Return to the Generic Dot Probe Task (Text) page
						
						GENERIC DOT PROBE TASK - with word stimuli (top/bottom)

SCRIPT INFO

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 06-05-2015
last updated: 04-19-2017 by K.Borchert (katjab@millisecond.com) for Millisecond Software LLC

Copyright © 04-19-2017 Millisecond Software


BACKGROUND INFO

											*Purpose*

This script implements a generic dotprobe procedure with words. It is based on the procedure published in:

Miller, M.A. & Fillmore, M.T (2010). The effect of word complexity on attentional bias
towards alcohol-related words in adult drinkers. Addiction, 105, 883–890.

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)



											  *Task*
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.


DATA FILE INFORMATION: 
The default data stored in the data files are:

(1) Raw data file: 'GenericWordDotProbe_raw*.iqdat' (a separate file for each participant)

build:												Inquisit build
computer.platform:									the platform the script was run on
date, time, subject:								date and time script was run with the current subject
/task:												1 = practice; 2 = test	
blockcode, blocknum:								the name and number of the current block
trialcode, trialnum: 								the name and number of the currently recorded trial
														(Note: not all trials that are run might record data) 
/category:											1 = Category1 ; 2 = category2 
/congruence:										1 = probe and target position same; 2 = probe and target position different
/target_position:									1 = target word on bottom; 2 = target word on top 
/target_y-probe_y:									the x-coordinate (in %) of the target / comp ('paired with target') /probe stims
/itemnumber:										itemnumber of currently selected text
/target_word:										stores the currently presented target word
/comp_word:											stores the currently presented comp ('paired with target') word
response:											the participant's response (scancode of response button)
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

(2) Summary data file: 'GenericWordDotProbe_summary*.iqdat' (a separate file for each participant)

script.startdate:									date script was run
script.starttime:									time script was started
script.subjectid:									subject id number
script.groupid:										group id number
script.elapsedtime:									time it took to run script (in ms)
computer.platform:									the platform the script was run on
/completed:											0 = script was not completed (prematurely aborted); 1 = script was completed (all conditions run)

/fixationduration/targetduration:					the duration of the fixation cross (default: 500ms)/the targets (default: 1000ms)/
/probeduration:										the duration of the probe presentation (default: 1000ms)

/iti:												intertrial interval in ms
/probe:												the symbol used for the probe (default: X)
/responsekey_bottom-responsekey_top:				the keyboard scancodes associated with bottom probe and top probe
/responsekey_bottom_label:							responsekey labels
/minimum_latency:									the minimum latency of a correct response that is included into summary variables
													(default: 100ms)

NOTE: 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

/propcorrect_congruent_category1:					proportion correct in congruent Category1 trials 
/propcorrect_incongruent_category1:					proportion correct in incongruent Category1 trials 
/meanRT_congruent_category1:						mean latency of congruent Category1 trials
/meanRT_incongruent_category1:						mean latency of incongruent Category1 trials
/AB_category1:										Attentional Bias for Category1 pics : If AB_category1 > 0 => faster mean latencies to congruent category1 trials (target and probe congruent)than incongruent ones

/propcorrect_congruent_category2:					proportion correct in congruent Category2 trials 
/propcorrect_incongruent_category2:					proportion correct in incongruent Category2 trials 
/meanRT_congruent_category2:						mean latency of congruent Category2 trials
/meanRT_incongruent_category2:						mean latency of incongruent Category2 trials
/AB_category2:										Attentional Bias for Category2 pics : If AB_category2 > 0 => faster mean latencies to congruent category2 trials (target and probe congruent)than incongruent ones


EXPERIMENTAL SET-UP
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
						Note: all 80 trials are randomly sampled without replacement

						DEFAULT TRIAL SEQUENCES
						fixation cross (500ms) -> target word pair (1000ms) -> tp_isi (0ms) -> probe (max. 1000ms)	(latency measured from onset of probe until response or offset of probe; whichever comes first)

STIMULI
generic text stimuli - insert your own under section Editable Stimuli
stimuli are presented in white on a black background

TASK INSTRUCTIONS
can be easily edited under EDITABLE CODE -> Editable Instructions

INSTRUCTIONS TO ADD CATEGORIES
go to section INSTRUCTIONS HOW TO ADD ADDITIONAL CATEGORIES

EDITABLE CODE:
check below for (relatively) easily editable parameters, stimuli, instructions etc. 
Keep in mind that you can use this script as a template and therefore always "mess" with the entire code to further customize your experiment.

The parameters you can change are:

/fixationduration/targetduration:				the duration of the fixation cross (default: 500ms)/the targets (default: 1000ms)
/tp_isi:										target-probe interstimulus interval in ms (0ms)
/probeduration:									the duration of the probe presentation (default: 1000ms)
												Note: by default this scripts allows for responses for the entire probe duration;
												the trial terminates after parameters.probeduration is over

/iti:											intertrialpause in ms (default: 0ms)
/probe:											the symbol used for the probe (default: X)
/responsekey_bottom:								the scancode of the bottom response button (default: 18)
/responsekey_top:								the scancode of the bottom response button (default: 23)
/responsekey_bottom_label:						the label of the bottom response button ("E")
/responsekey_top_label:							the label of the top response button ("I")
/minimum_latency:								the minimum latency of a correct response that is included into summary variables
												(default: 100ms)

Physical Settings of Display:					Note: change the settings to optimize the display on your computer screen
/target_bottom_y-target_top_y:					the y-coordinate in % of the top/bottom target (default: 35%, 65%)
/target_x:										the x-coordinate of the target (default: center at 50%)
/fixationcross_height:							the height of the fixation cross in canvas height percentage (default: 5%)
/probe_height:									the height of the probe in canvas height percentage (default: 5%)
/wordheight:									the height of the word in canvas height percentage (default: 5%)

Copyright © Millisecond Software. All rights reserved.
Contact | Terms of Service | Security Statement | Employment