Psychotoolboxを使う

最近使い始めた心理実験やfMRI・EEG実験に用いる視聴覚刺激を作成するMATLABのツールボックス、Psychotoolboxについての防備録。

（DLの方法など詳細については、ググってください）

1. Screen関数について

[VBLTimestamp StimulusOnsetTime FlipTimestamp Missed Beampos] = Screen('Flip', windowPtr [, when] [, dontclear] [, dontsync] [, multiflip]);

事前にセットされた描画情報を表示する。

windowPtr： window番号を入力する。windowPtr = Screen('Open',0,0)などで得られる。"windowPtr" is the id of the onscreen window whose content should be shown at

flip time.

when：　"when" specifies when to flip: If set to zero (default), it will flip

on the next possible video retrace. If set to a value when > 0, it will flip at

the first video retrace after system time 'when' has been reached.

dontclear：　"dontclear" If set to 1, flip will not clear the framebuffer after Flip - this allows

incremental drawing of stimuli. The default is zero, which will clear the

framebuffer to background color after each flip. A value of 2 will prevent Flip

from doing anything to the framebuffer after flip. This leaves the job of

setting up the buffer to you - the framebuffer is in an undefined state after

flip.

dontsync：　"dontsync" If set to zero (default), Flip will sync to the vertical

retrace and will pause execution of your script until the Flip has happened. If

set to 1, Flip will still synchronize stimulus onset to the vertical retrace,

but will *not* wait for the flip to happen: Flip returns immediately and all

returned timestamps are invalid. A value of 2 will cause Flip to show the

stimulus *immediately* without waiting/syncing to the vertical retrace.

multiflip：　"multiflip" defaults to zero: If set to a value greater than zero, Flip will

flip *all* onscreen windows instead of just the specified one. This allows to

synchronize stimulus onset on multiple displays, e.g., for multidisplay stereo

setups or haploscopes. You need to (somehow) synchronize all attached displays

for this to operate tear-free. Flip (optionally) returns a high-precision

estimate of the system time (in seconds) when the actual flip has happened in

the return argument

ex) fixation point と barを表示

%凝視点の線分座標

FixationXY =...

      [-20, 20,  0,  0;

         0, 0, -20, 20];

AttentionBarXY =...

      [-390, -390, 390, 390;

       30,  -30,  30, -30];

Screen('DrawLines', win, FixationXY, 2, [255 0 0], [centerX, centerY]);

Screen('DrawLines', win, AttentionBarXY, 3, [255 255 255], [centerX, centerY]);

Screen('Flip', win);

1.