Trait Judgements of Faces - Online Experiment

By Yue Xu · hyue.xu@gmail.com

Last verified: Nov 10, 2025

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Overview

This repository hosts HTML-based code built with JsPsych for the online experiment described in the manuscript "Trait judgments of faces using a task without word labels" (OSF preprint).

The repository demonstrates:

• Consent form collection
• Participants' physical screensize measurement
• Instruction reading and comprehension quizzes with response-based feedback
• Participant prescreening and eligibility gating
• Several end-task questionnaires in multiple formats
• Gatekeeping is implemented at each step: participants must meet specific criteria to proceed to the next stage.

Note:

• The Cambridge Face Memory Test (CFMT) and Multi-Arrangement (MA) task are not included here due to external hosting.
• See Experimental_Paradigm.pdf for a detailed walkthrough, screenshots, and demo links.
• Data analysis scripts and datasets are available on the OSF project files and the Github repo.

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Experiment Flow

Each section of the experiment consists of HTML files hosted on a web server. URL parameters are passed between sections to maintain participant identifiers and task performance data.

Stage 1 - Prescreening and Qualification:

1. Part 1: Consent Form and Screen Calibration
   File: Stage1_Part1_intro-and-calibration.html

   • Demo Link: https://www.yxu.caltech.edu/experiment_demo/MA_experiment_demo/Stage1_Part1_intro-and-calibration.html
   • Obtain consent and ensure that participants use an adequate screen size (≥7-inch diagonal) and laptops/destops instead of cellphones/tablets.
   • Parameters read (these are passed forward to subsequent tasks):

     ?participantId=XXXX1&assignmentId=XXXX2&projectId=XXXX3
     

2. Part 2: Cambridge Face Memory Test (CFMT)
   Not included in this repository.

   • Hosted on Testable.org. This link provides a short demo and allows researchers to request access to this portion of the task.
   • We modified the original CFMT into a shortened version as described in the manuscript. On Testable.org, the task was further adapted to :
     • Update a variable to accumulate the total number of correctly answered questions after each trial, and
     • Automatically pass the result (as a URL parameter) to the next section of the experiment.

       &CFMT=XX
       

   • If you are interested in implementing a similar customization, please follow the testable manual and feel free to contact the authors for details.

3. Part 3: Instruction Reading and Quiz
   File: Stage1_Part3_instruction-and-quiz.html

   • Demo Link: https://www.yxu.caltech.edu/experiment_demo/MA_experiment_demo/Stage1_Part3_instruction-and-quiz.html
   • Participants read detailed instructions and complete a 7-question comprehension quiz.
   • If the following criteria are not met, participants are redirected to an end screen:
     • CFMT score must be ≥33/48, and
     • Quiz score must be ≥6/7.

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Stage 2 – Main Task and End Questionnaire

1. Part 1: Multi-Arrangement Task (MA Task)
   Not included in this repository.

   • Hosted on meadows-research.com
   • A toy demo available at: https://meadows-research.com/demos/multiarrange/

2. Part 2: End-Task Questionnaire (modified version for Experiment 2)
   File: end_task_questionnaire.html

   • Demo Link: https://www.yxu.caltech.edu/experiment_demo/MA_experiment_demo/end_task_questionnaire.html
   • An additional URL parameter is passed from the previous section:

     &mead_name=XXXXXX
     

     which stores the participant’s assigned Meadows ID.

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Technical Setup

URL Parameters

Ensure that URL parameters are correctly passed to maintain continuity between parts of the experiment and record participant data accurately.

Typical parameters:

Parameter	Description
participantId	Participant unique ID
assignmentId	MTurk assignment ID
projectId	Internal project or study ID
CFMT	CFMT score (used for gating only after the CFMT section)
mead_name	Meadows system participant ID (added in Stage 2)

If any are missing, they default to "XXXXXXXnotValid".

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Data Saving and Permissions

File Permissions

• Make sure to update the file permissions each time after adding or updating files:

  chmod -R 755 *       # all files
  chmod 733 data/      # write-only, not listable

Data Saving Mechanism

• Data are saved asynchronously to the /data/ folder via POST requests, at the end of each section.
• Known issue: rare save failures.
  This is yet to be implemented: a robust implementation should include a retry loop that waits briefly before resubmitting until a "success" response is received.

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Hosting and Deployment

• The server must support dydnamic requests (not a static-only host).

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How to Cite

If you use this experiment framework or adapt its code, please cite the associated manuscript(s) from this project (osf preprint).

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Contact

Yue Xu: hyue.xu@gmail.com