goxpyriment

Parity Decision

A simple even/odd decision task on single digits (0–9). Each digit appears at the centre of the screen; the participant presses a key to indicate whether it is even or odd. Reaction times and accuracy are recorded.

This example is useful as a minimal working experiment and as a starting point for building more complex tasks.

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Trial structure

Fixation cross  →  Digit  →  Response  →  ITI
    500 ms        until key   key press    500 ms

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Response keys

Key	Meaning
F	Even
J	Odd

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Prerequisites

• Go 1.25+
• SDL3 development libraries (sudo apt install libsdl3-dev on Ubuntu/Debian)

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Running

# Fullscreen, participant 1
go run main.go -s 1

# Windowed (development / testing)
go run main.go -s 1 -d

Flags

Flag	Default	Description
-s	0	Participant ID (integer)
-d	off	Development mode: windowed 1024×768

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Output

Data are saved to goxpy_data/ as a .xpd file (CSV with a metadata header). One row per trial:

Column	Description
number	The digit shown (0–9)
key	Key pressed
rt	Reaction time in milliseconds
correct	Whether the response was correct

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