psychopy.SpatialSuppressMotion-v0

class neurogym.envs.psychopy.spatialsuppressmotion.SpatialSuppressMotion(dt=8.3, win_kwargs={'size': (100, 100)}, timing={'stimulus': 300}, rewards=None)[source]

By Ru-Yuan Zhang (ruyuanzhang@gmail.com)

Spatial suppression motion task. This task is useful to study center-surround interaction in monkey MT and human psychophysical performance in motion perception.

Tha task is derived from (Tadin et al. Nature, 2003). In this task, there is no fixation or decision stage. We only present a stimulus and a subject needs to perform a 4-AFC motion direction judgement. The ground-truth is the probabilities for choosing the four directions at a given time point. The probabilities depend on stimulus contrast and size and the probabilities are derived from emprically measured human psychophysical performance.

Parameters:

  • <dt> – millisecs per image frame, default: 8.3 (given 120HZ monitor)

  • <win_size> – size per image frame

  • <timing> – millisecs, stimulus duration, default: 8.3 * 36 frames ~ 300 ms. This is the longest duration we need (i.e., probability reach ceilling)

Note that please input default seq_len = 36 frames when creating dataset object.

Reference paper

Perceptual consequences of centre?surround antagonism in visual motion processing

Tags

perceptual, tag-plaid, tag-motion, tag-center-surround

Sample run
static envelope(time_sigma, frame_rate=120, cut_off=True, amplitude=128)[source]

envelope(time_sigma, frame_rate=120, cut_off=True):

Create a temporal profile and mv_length to motion stimulus in the spatial suppression task. This function is modified fron Duje Tadin’s code.

Not critical, we can use a square temporal profile

Arg:

<time_sigma>: in secs, sigma of temporal envelope <frame_rate>: int, hz, monitor frame rate <cut_off>: default: True. Whether to cut <amplitude>: int, 128.

We return the tempora modulation <profile> and an int indicating <mv_length>.

This function is adoped from Duje Tadin. Some variables here are not clear.

getgroundtruth(trial)[source]

The utility function to obtain ground truth probabilities for four direction

Input trial is a dict, contains fields <duration>, <contrast>, <diameter>, and <direction>.

We output a (4,) tuple indicate the probabilities to perceive left/right/up/down direction. This label comes from emprically measured human performance