Return to the Garner Interference Task page

Script Author: Katja Borchert, Ph.D. ( for Millisecond Software, LLC
Date: 03-05-2013
last updated: 01-11-2016 by K.Borchert ( for Millisecond Software LLC

Copyright © 01-11-2016 Millisecond Software


This script implements a Garner Interference Task as described in (Experiment1):

Ridderinkhof, K. R., van der Molen, M. W., Band, P. H., & Bashore, T. R. (1997). Sources of interference 
from irrelevant information: A developmental study. Journal of Experimental Child Psychology, 65, 315–341.

Participants view a box in the middle of the screen. Inside the box is a line that can be tilted to the left
or right (or it can be a simple vertical line in a control condition when no tilt changes should occur). 
The color of the box or the color of the line itself can change from red to blue 
(if the color of the line is changing, the color of the box is held constant at yellow; 
ditto if the color of the box is changing; if no color changes should occur at all the line or the box can 
further have the color purple). Participants are instructed to pay attention to only one dimension (=relevant dimension)
a) the tilt of the line OR b) the color of either the box (separated condition) or the line itself (integrated condition) 
and ignore changes in the other (irrelevant) dimension as best as they can. The actual task they have to do is a simple 
categorization task: if the line tilts to the right, press a certain key. If the line tilts to the left, 
press another key. Same for the color tasks.

The default data stored in the data files are:

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

build:										Inquisit build
computer.platform:							the platform the script was run on
date, time, subject, group:					date and time script was run with the current subject/groupnumber 
blockcode, blockcount:						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) 
/practice:									1 = practice blocks; 0 = experimental blocks
/dimension:									target dimension: 1 = color; 2 = tilt
/dim_config: 								1 = integrated; 2 = separated
/variationtype:								1 = orthogonal; 2 = correlated; 3 = control
/target:									"color1" vs. "color2" vs. "tilt1" vs. "tilt2"
/responsekeycongruence:						0 = congruence doesn't apply; 1 = color and tilt response keys congruent; 2 = color and tilt response keys incongruent
response:									the participant's response (scancode of response button)
correct:									the correctness of the response (1= correct; 0 = error)
latency: 									the response latency (in ms)
/ITI:										stores the current ITI (in ms)

(2) Summary data file: 'GarnerInterferenceTask_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; 1 = script was completed (all conditions run)

/meanrt_tilt_control_separated:		calculates the mean reaction times (in ms) to correct responses in a given condition
/propcorrect_color_ortho_integrated (etc):	calculates the proportion correct in a given condition
											(here: color, ortho, integrated)

2 Dimensions (Color vs. Orientation), blocked-format x 
2 Dimensional Configurations (integrated vs. separated), blocked-format x
3 Variation Type (control, correlated, orthogonal), blocked-format

(A) Color vs. Dimension: color changes (red <-> blue) vs. changes in the tilt of the line (left <-> right)
if relevant dimension is color: the color of the unattended configuration is held yellow
if relevant dimension is tilt and no color changes should occur at all: box and line are purple
(red+blue -> purple)
(B) Integrated vs. Separated: color changes of the line itself vs. color changes of the box surrounding the line

(C) Control vs. correlated vs. orthogonal:
Control: only changes in the relevant dimension occur; the irrelevant dimension is held constant
Correlated: changes in the relevant dimension are tied to (dependent on) changes in the irrelevant dimension
	2 possible matches: 
		congruent  -> both changes require the same response or
		incongruent -> both changes require opposite responses
Orthogonal: changes in the relevant dimension are independent of changes in the irrelevant dimension
(some of the combinations are congruent vs. some are incongruent)

=> 12 different block types, tested all within-subjects

(a) 4 practice blocks (with error feedback)
(b) 12 experimental blocks: each block consisted of 48 trials; left/right responses occur equally often (no feedback)
(c) A rest block in between each block

Use of response keys (default: A and L keys) is counterbalanced across participants. Assignment is done by groupnumber to 
any of the 4 possible key combination conditions.

!Note: The location of the (default) response keys (right "L" or left "A" on the keyboard) could introduce the potentially 
unwanted variable  "compatibility with tilt direction". 
To avoid, use 
(a) different response keys (change under Editable Parameters) or different inputdevice (e.g. joystick) altogether OR
(b) different stimuli: A set of possible alternative stimuli is provided under section Editable Stimuli -> item.lines
The set of alternative stimuli are Vs that differ in whether they are upside down or rightside up (replacing the direction
of left vs right). The composite stimulus for the color control condition is a diamond as it contains both V directions.

can be edited under section Editable Instructions

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:

/line_fontheight:				sets the height of the lines in % screen height (default: 20%)

/responsekey1:					sets the scancode of the response key 1 (here: 30)
/responsekey1_label:			the label of response key 1 (default: "A")
/responsekey2: 					sets the scancode of the response key 2 (here: 38)
/responsekey2_label:            the label of response key 2 (default: "L")

/color1:						sets the first target color (here: red)
/color2:						sets the second target color (here: blue)
/alternativecolor1:				sets the first alternative color (here: yellow)
/alternativecolor2:				sets the second alternative color (here: purple), used in control
								condition when color is held constant and only tilt is changing

/responsetimeout:				sets how much time participants have to respond in ms (here: 5000ms)

/regularresttime:				rest time after each block in ms (default: 60000s)
/prolongedresttime:				rest time during specified long rest blocks in ms (default: 300000)
/prolongedrest:					determines after how many blocks a prolonged rest block should be given (default:10)

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