How to make fluid biomotion walkers

Hi,

I'm new here and I'm not sure if this is the right forum to post this but here goes.

I'm dealing with a code that displays biomotion point light walkers. However, I have a problem with its fluidity. It's not fluid. It makes a brief stop motion before re-starting its cycle. Can anyone help me on this?

Here is the full code:

(Btw, this code is written on Matlab version 7.6.0.324 (R2008a) using PsychToolbox 2.) ------------------------------------------------------------ clear all; clc; rand('state',sum(100*clock)) wptr = 0; %%%%%%%%%%%%%%%%%%%%%%%%%%%%

load walkers56;

vecty=VectLeftY vectx=VectLeftX starty=StartLeftY startx=StartLeftX

[NumFrames, NumDots, NumMovies] = size(vectx); % 20 12 50

%%%%%%%%%%%%%%%%%%%%%%

DotSz = 7; DotColor = 0; bkgdColor = 127; stimRect = [0 0 1440 900];

FrameX = 158; FrameY = 275; ShiftRad = 30;

NumCycles = 1 StimPerBlock = 4

ifi =120;

%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%% screen('CloseAll')

[w, wRect] = screen(wptr,'OpenWindow', bkgdColor,[],32);

screen(w, 'FillRect', bkgdColor, wRect);

[ctrx, ctry] = RectCenter(stimRect); ctrShiftX = ctrx-FrameX/2; ctrShiftY = ctry-FrameY/2;

fixRect = [0 0 11 11]; fixpt = screen(w, 'OpenOffscreenWindow', bkgdColor, fixRect); screen(fixpt, 'DrawLine', 0, 0, 5, 10, 5); screen(fixpt, 'DrawLine', 0, 5, 0, 5, 10);

for frame = 1:NumFrames stimpt(frame) = screen(w, 'OpenOffscreenWindow', bkgdColor, stimRect); screen('CopyWindow', fixpt, stimpt(frame), fixRect, CenterRect(fixRect, stimRect)); end %for frame

%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%

start = GetSecs;

screen(w, 'FillRect', bkgdColor, wRect); HideCursor; screen('CopyWindow', fixpt, w, fixRect, CenterRect(fixRect, wRect));

posx = startx(1, :, pick)+900; posy = starty(1, :, pick)+320;

posxRight = StartRightX(1, :, pick); posyRight = StartRightY(1, :, pick);

%elseif StimType == 0 & (samediff ==0 | stim == 1)

posx2 = posxRight+1000; posy2 = posyRight+320;

        posx3 = posx+200;
        posy3 = posy;

for cycle = 1:NumCycles*2 for stim = 1:StimPerBlock trialStart = GetSecs;

% if (samediff ==0 | stim == 1), pick = 1

      end

for frame = 1:NumFrames for dot= 1:NumDots

left = posx2(dot) + VectRightX(frame, dot, pick); top = posy2(dot) + VectRightY(frame, dot, pick);

                left2=posx3(dot) + vectx(frame, dot, pick); 
                top2=posy3(dot) + vecty(frame, dot, pick);

                left1=posx(dot) + vectx(frame, dot, pick); 
                top1=posy(dot) + vecty(frame, dot, pick);

screen(stimpt(frame),'FillOval',DotColor, [left1 top1 left1+DotSz top1+DotSz]); screen(stimpt(frame),'FillOval',DotColor, [left2 top2 left2+DotSz top2+DotSz]); screen(stimpt(frame),'FillOval',DotColor, [left top left+DotSz top+DotSz]); end %for dot end %for frame

for frame = 1:NumFrames screen(w,'WaitVBL', 1); screen(w,'WaitVBL', ifi); screen('CopyWindow',stimpt(frame),w,stimRect,CenterRect(stimRect, wRect)); screen(stimpt(frame), 'FillRect', bkgdColor, stimRect); screen('CopyWindow', fixpt, stimpt(frame), fixRect, CenterRect(fixRect, stimRect));

    end %for frame & biomotion

% end %for stim end %for cycle

ended_session=GetSecs; session_dur = ended_session - start

screen(w, 'FillRect', bkgdColor, stimRect); screen('CopyWindow', fixpt, w, fixRect, CenterRect(fixRect, wRect));

%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%

for frame = 1:NumFrames screen(stimpt(frame), 'Close') end

screen('CloseAll') % clear -----------------------------------------------------------------------