___________________________________________________________________________________________________________________ DIFFERENCE THRESHOLD: ADJUSTMENT METHOD (Example: determine difference threshold for a red) ___________________________________________________________________________________________________________________ Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC Date: 01-20-2014 last updated: 02-21-2022 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC Script Copyright © 02-21-2022 Millisecond Software ___________________________________________________________________________________________________________________ BACKGROUND INFO ___________________________________________________________________________________________________________________ This script implements the ADJUSTMENT METHOD to estimate the difference threshold for a particular color red Reference: Ehrenstein, W.H. & and Addie Ehrenstein, A. (1999). Psychophysical Methods. In U. Windhorst & H. Johansson, Hakan (Eds.), Modern Techniques in Neuroscience Research (pp.1211-1241). Heidelberg: Springer. (->http://uni-leipzig.de/~isp/isp/history/texts/PSYPHY-M.PDF) ___________________________________________________________________________________________________________________ TASK DESCRIPTION ___________________________________________________________________________________________________________________ Participants are asked to adjust a red Target color until the red color of the Target is as red as the given red Base color. Adjustments are made with keyboard input (D = decrease red target color; L = increase red target color) ___________________________________________________________________________________________________________________ DURATION ___________________________________________________________________________________________________________________ the default set-up of the script takes appr. 2 minutes to complete ___________________________________________________________________________________________________________________ DATA FILE INFORMATION ___________________________________________________________________________________________________________________ The default data stored in the data files are: (1) Raw data file: 'adjustmentmethod_raw*.iqdat' (a separate file for each participant) build: The specific Inquisit version used (the 'build') that was run computer.platform: the platform the script was run on (win/mac/ios/android) date, time: date and time script was run subject, group: with the current subject/groupnumber session: with the current session id blockcode, blocknum: the name and number of the current block (built-in Inquisit variable) trialcode, trialnum: the name and number of the currently recorded trial (built-in Inquisit variable) Note: trialnum is a built-in Inquisit variable; it counts all trials run; even those that do not store data to the data file. adjustcycles: stores the number of adjustment cycles run baseline_value: stores the color of the current base target_value: stores the color of the current target direction: 1 = Down (sequence starts with targetvalue > baseline value) 2 = Up (sequence starts with targetvalue < baseline value) sequencecount: counts how many adjustment sequences have been run response: the participant's response latency: the response latency in ms diffthreshold_up: the estimated Difference threshold for the current UP sequence (= starting with target value < baseline value) diffthreshold_down: the estimated Difference threshold for the current DOWN sequence (= starting with target value > baseline value) MeanDiffThreshold: mean difference threshold for one adjustment cycle (up and down) (2) Summary data file: 'adjustmentmethod_redcolor_summary*.iqdat' (a separate file for each participant) inquisit.version: Inquisit version run computer.platform: the platform the script was run on (win/mac/ios/android) startdate: date script was run starttime: time script was started subjectid: assigned subject id number groupid: assigned group id number sessionid: assigned session id number elapsedtime: time it took to run script (in ms); measured from onset to offset of script completed: 0 = script was not completed (prematurely aborted); 1 = script was completed (all conditions run) step: the decrease in target value everytime participants adjusts (default: 1) adjustcycles: stores the number of adjustment cycles run parameters.baselinevalue1: the default baseline value for the first adjustment cycle diffthreshold1: mean difference threshold for the first adjustment cycle (both up and down) __________________________________________________________________________________________________________________ EXPERIMENTAL SET-UP ___________________________________________________________________________________________________________________ By default this scripts estimates the Difference Thresholds for 1 Base color (-> editable values), with 2 sequences (one where the targets starts out lighter and one where the target starts out darker, order randomly determined). The thresholds are the red color components of the target when participants decide that they are the same (aka press 'ENTER'). The overall threshold is the mean of the "up" and "down" thresholds. ___________________________________________________________________________________________________________________ INSTRUCTIONS ___________________________________________________________________________________________________________________ see section Editable Instructions ___________________________________________________________________________________________________________________ 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: /baselinevalue1: the baseline red value for the first adjustment cycle (0 -> black, 255 -> brightest red) Note: to add adjustment cycles with different basevalues add a value for each new baseline value you want to test and go to BLOCKS for further instructions. /step: the decrease in target value everytime participants adjusts (default: 1) /initialdifference: initial difference in the red component of target and base (default: 50) /interadjustmentpause: pause after an adjustment sequence (default: 500ms)