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										VISUAL SEARCH
										(behavioral data only; no eyetracking)
SCRIPT INFO

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 06-19-2017
last updated: 06-26-2017 by K.Borchert (katjab@millisecond.com) for Millisecond Software LLC

Script Copyright © 06-26-2017 Millisecond Software


BACKGROUND INFO 

											*Purpose*
This script implements a basic visual search paradigm based on:

Motter,B.C., & Simoni, D.A. (2008). Changes in the functional visual field during search with and without
eye movements. Vision Research 48 (2008) 2382–2393.

											  *Task*

Participants are asked to check letter arrays of green and red L's and T's (in 6 different spatial rotations)
of varying array sizes (6, 12, 24, 48) for a target letter. 
The target letter shares one feature with each distractor letter ("conjunction style search array"). 
For example, if the target letter is a red L, the distractor letters are red T's and green L's. 
Half the arrays contain the target.


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

(1) Raw data file: 'visualsearch_letters_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, 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; by default data is collected unless /recorddata = false is set for a particular trial/block) 

/arraySize:						stores the number of stims presented (6, 12, 24, 48)									
/targetPresent:					1 = target presented in array; 0 = otherwise	
 picture.target.hposition:		the horizontal screen position (in % of canvas width)
 picture.target.vposition:		the vertical screen position (in % of canvas height)
/targetDistance:				calculates the distance (in %) from the target stim to the center (fixation cross)
								relative to the screen canvas (portion of monitor used for stimulus display)
								(only valid for 'Target Present' trials)
								-> the value can be converted to absolute measurements if the dimensions of the monitor are known
								(also needed: expressions.canvasRatio)	
/canvasRatio:					calculates the ratio of canvas (=the part of the screen that is used by the script) height to height 
								of monitor	(in %)	

/currentTarget:					stores the itemnumber of the current target item cue								
response:						the participant's response (scancode of response button: 18(E); 23(I))
/response:						translates scancode of response button into response: 'yes' vs. 'no
correct:						accuracy of response: 1 = correct response; 0 = otherwise
latency: 						the response latency (in ms); measured from: onset of stims (after presentation of cue)


(2) Summary data file: 'visualsearch_letters_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)
/ACCoverall:					overall proportion correct (across all test trials)
/meanRT:						mean latency (in ms) across all correct test trials

/ACCtargetPresent_6:			proportion correct of trials with 6 stimuli where the target is present
/RTtargetPresent_6:				mean correct latency (in ms) of trials with 6 stimuli where the target is present
/ACCtargetAbsent_6:				proportion correct of trials with 6 stimuli where the target is absent
/RTtargetAbsent_6:				mean correct latency (in ms) of trials with 6 stimuli where the target is absent

/ACCtargetPresent_12:			proportion correct of trials with 12 stimuli where the target is present
/RTtargetPresent_12:			mean correct latency (in ms) of trials with 12 stimuli where the target is present
/ACCtargetAbsent_12:			proportion correct of trials with 12 stimuli where the target is absent
/RTtargetAbsent_12:				mean correct latency (in ms) of trials with 12 stimuli where the target is absent

/ACCtargetPresent_24:			proportion correct of trials with 24 stimuli where the target is present
/RTtargetPresent_24:			mean correct latency (in ms) of trials with 24 stimuli where the target is present
/ACCtargetAbsent_24:			proportion correct of trials with 24 stimuli where the target is absent
/RTtargetAbsent_24:				mean correct latency (in ms) of trials with 24 stimuli where the target is absent

/ACCtargetPresent_48:			proportion correct of trials with 48 stimuli where the target is present
/RTtargetPresent_48:			mean correct latency (in ms) of trials with 48 stimuli where the target is present
/ACCtargetAbsent_48:			proportion correct of trials with 48 stimuli where the target is absent
/RTtargetAbsent_48:				mean correct latency (in ms) of trials with 48 stimuli where the target is absent

* separate data files: to change to one data file for all participants (on Inquisit Lab only), go to section
"DATA" and follow further instructions


EXPERIMENTAL SET-UP

Practice: default
- 24 practice trials (6 per target category, e.g. 'green L', order is randomized)
- each possible target is used once per target category - random selection)
- 2 different array sizes per target category (4 stims vs. 16 stims), random selection
- half the trials (12) have the target present (order of 'target present' vs. 'target absent' randomized)
- provides performance feedback


Test: default 
2 target colors (green vs. red) x 2 target letters (L vs. T) x 4 array sizes (6, 12, 24, 48) x 2 target condition (present vs. absent) 
x 6 reps = 192 trials, 
tested in a full, mixed design

- the 4 target categories (color x letter) are selected in random order
- in each of the 4 target conditions (color x letter, e.g. 'green L'): 
	- equal frequency of the 4 possible array sizes (array size is randomly determined)
	- half the targets are present, half the targets are absent (randomly selected)
		=> balanced across the 4 different set sizes (6 targets present/6 targets absent for each of the 4 set sizes)
		Note: Motter & Simoni (2008) ran sessions of 240 trials.
	
- Target Selection:
	- The target stimulus is selected randomly from the 6 possible rotations (see under STIMULI) for the given target condition)
	- each rotation is selected equally often 
	=> each target rotation is run 8 times per target condition
	
- Distractor Selection:
		- half the distractors are selected from the opposite color (but same letter)
			-> the appropriate item numbers are selected randomly without replacement (repetitions are possible, once all 6 possible stims were selected)
		- the remaining distractors are selected from the same color (but different letter)
			-> the appropriate item numbers are selected randomly without replacement (repetitions are possible, once all 6 possible stims were selected)

- Stim Locations:
	- 48 possible stim locations (7x7 matrix, with fixation cross in the center)
	- stim locations are randomly (without replacement) assigned to each of the stims (including target)
	- stim locations reset before each new trial


Canvas:
By default, the canvas (=part of the screen used by this script) is the biggest square (width = height) that can be
established on the current monitor. The canvas can be further manipulated by explicitly forcing
a specific canvas size and/or by forcing a specific windowsize (see section DEFAULTS for more info)	
	

Trial Sequence:
Fixation Cross (until Spacebar press) -> Cue (default: 1000ms)->Array (max: 7000ms)
	
	
STIMULI
provided by Millisecond Software - can be edited under section Editable Stimuli

Note:
each target category (green L, red L, green T, red T) can be represented by 1 of 6 orientations:
the letter was rotated 6 times by increments of 60deg


INSTRUCTIONS
provided by Millisecond Software as htm files - to edit, edit the htm files directly

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:


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