psychmetal

Native Metal stimulus presentation on Apple silicon Macs, from Python, with an interface resembling Psychtoolbox's Screen. There is no OpenGL anywhere in the path. The same engine serves PsychMetal for MATLAB and Octave.

Version 0.7.0 also supports iPhone/iPad through a separately built app: see iOS instructions. The GitHub release includes blob_array_demo.py, a labelled counterphasing array with mouse or one-finger dragging.

Install it into a virtual environment. Homebrew's Python (and any Python following PEP 668) refuses packages installed outside one:

python3 -m venv ~/venvs/psychmetal          # once
source ~/venvs/psychmetal/bin/activate      # in each new Terminal window
pip install psychmetal

Requires macOS 14 or later on Apple silicon, an arm64 Python 3.10 or later, and numpy.

import psychmetal as pm

with pm.open_window(0, [0, 0, 0]) as (w, rect, ifi):
    pm.fill_rect(w, [255, 0, 0], [100, 100, 300, 300])
    vbl, onset, flip_return, missed, slipped = pm.flip(w)
    pm.wait_secs(1)

Each PsychMetal command is a function with the snake_case name and the same arguments, order and defaults as in MATLAB; MATLAB's [] is None. Colours run 0–255 by default. Key indices are 0-based (kb_name('ESCAPE') is 40). Several rectangles, dot positions and per-item colours keep MATLAB's 4xN, 2xN and 3xN/4xN orientation, and images are numpy arrays (H, W[, C]) in any memory layout, read without copying. help(psychmetal) covers threading, batching and the other details.

Demos and hardware checks (Gabors, dynamic noise, textures, dot motion, keyboard, an inventory of every command) are in the repository's python folder.

Flip timestamps come from Metal's presentation reports, not a photodiode. See the repository for validation and its limits.

MIT license.