Return to the Serial Probe Recognition Task page

Script Author: Katja Borchert, Ph.D. ( for Millisecond Software, LLC
Date: 03-20-2015
last updated:  12-01-2015 by K.Borchert for Millisecond Software LLC

Copyright ©  12-01-2015 Millisecond Software


This script runs a Serial Probe Recognition Task similarly to the one described in:

Sands, S. F., & Wright, A. A. (1980). Serial probe recognition performance by a rhesus monkey and a human 
with 10- and 20-item lists. Journal of Experimental Psychology: Animal Behavior Processes, 6, 386–396.

The default set-up runs the procedure for people (no feedback markers are sent; positive auditory feedback for correct responses).
To send feedback markers, please go to 
a) section Editable Values and set feedback durations and
b) and follow further instructions.

Computer presents lists of 10 picture stimuli; each stimuli is presented for 1s with a 800ms interstimulus
interval in the top half of the computer monitor. 1s after the last list stimulus is presented, a probe
is presented in the lower part of the computer monitor. Participants have 2s to decide whether
the probe was part of the list.
Half the probes are negative (the probe was not part of the list);
half the probes are positive (the probe was part of the list) with each probe position (1-10) 
being represented equally often. 

The default data stored in the data files are:

(1) Raw data file: 'SerialProbeRecognition_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) 
/currentprobeposition:			stores the position of the probe in the set
/probestim:						stores the itemnumber of the probestim
stimulusitem:					the presented stimuli in order of trial presentation
response:						the participant's response
correct:						the correctness of the response (1 = correct; 0 = incorrect)
latency: 						the response latency (in ms)

/currentprobeposition:			stores the position of the probe in the set
/probestim:						stores the itemnumber of the probestim

(2) Summary data file: 'SerialProbeRecognition_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)
/propcorrect: 					overall proportion correct (across positive and negative probe trials)
									positive probe trial: probe is part of set
									negative probe trial: probe is not part of set
/propcorrect_negprobe:			overall proportion correct for negative probe trials
/propcorrect_posprobe:			overall proportion correct for positive probe trials
/propcorrect_probe10:			proportion correct responses for positive probe trials; separate for each probeposition

1 Block of 140 trial sequences
* 70 positive probe trials (7 per each of the 10 probe positions)
* 70 negative probe trials

The order of negative and positive probes (and probe positions) are randomly determined.
The items presented in each list are randomly selected.

trial sequence
* trial.start_positiveprobe/negativeprobe: resets crucial variables before each list starts and selects current probeposition
* trial.stimpresentation_positiveprobe: presents the list of 10 stimuli (each pic is presented for 1000ms with an isi of 800ms)
* trial.start_positiveprobe/negativeprobe: 1000ms after the last list item: presents the probe and waits for response for 2000ms 
* presents only positive audio feedback (4000hz sound) by default; to send feedback port information 
	-> go to and follow further instructions

in this script: 
210 images of animals, flowers, vegetables, and fruits (collected from the internet)
- 140 of these get randomly selected to be the list stimuli
=> results in repeats of stimuli after 14 lists (of 10 items) have been presented
(each item is repeated 10 times)
=> to avoid any repeats use: 1400 (+ 70 for the negative probes) list pictures for 140 trial sequences 
(or use shorter lists and/or fewer trials)

- 70 (default: parameters.nr_trials/2) of these 210 stims are randomly selected to be the negative probes (these are not used for the lists)
=> no repeats of negative probes

generic instructions provided by Millisecond Software.
To change, go to 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:

/nr_stims:									number of stimuli in a set
												Note: by default this script calculates summary variables for up to 10 possible probe positions
												Note: if this number is changed, go to list.probeposition and change possible probe positions

/nr_trials:									number of trials to run
/stimduration:								presentation duration of each of the stimuli in ms (default: 1000ms)
/regular_isi:								interstimulus interval between stimuli presentation in ms (default: 800ms)
/last_isi:									time between last stimulus and probe presentation in ms (default: 1000ms)
/probeduration:								duration of probe trial in ms (default: 2000ms)

/positivefeedbackduration:					duration of positive feedback in ms (default: 200ms)
/negativefeedbackduration:					duration of negative feedback in ms
												Note: to send positive or negative feedback markers go to and follow instructions

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