Brief reference

class stimuli.Grating(pos, params=Params())

A periodic modulation of luminance. The modulation is characterized by spatial and temporal frequencies. The stimulus is complete with a mask that can take the form of smooth (Gaussian) or sharp aperture. The grating can be tilted and slanted.

Parameters:

• width – size of stimulus in pixels
• fs – spatial frequncy
• ph – phase
• speed – speed
• contr – contrast

This stimulus can be also used with the “Pelli-Zhang Video Switcher”. The following parameters apply:

Parameters:

• box – logical True or 1.0 to enable Video Switcher
• Lbg – Luminance of background
• Lmin – Minimum measured luminance of monitor
• Lmax – Maximum measured luminance of monitor
• gamma – gamma correction constant
• BTRR – the BTRR parameter of you Video Switcher

class stimuli.DotLattice(pos, params=Params())

A periodic array of dots organized along several orientations with a constant inter-dot distance within orientation. The “dots” can be solid disks or Gaussian blobs, or they can have more complex shapes, such as luminance gratings characterized by the same of different spatial frequencies and orientations.

Parameters:

• ap_fs – spatial frequency of the mask
• ap_sigma – spatial frequency of the mask
• ap_edge – power of apperture’s Gaussian (slope)
• gamma – angle
• theta – angle of A nd B directions within lattice
• dx – parameter a, shortest distance
• r – aspect ratio
• dot_size – size of dot’s texture
• dot_sigma – width of dot’s Gaussian
• dot_fs – spatial frequency of dot’s grating
• dot_edge – power of dot’s Gaussian (slope)
• dot_c – dot color [0.0,1.0]
• dot_phi – phase of dot’s grating

class stimuli.Dot(pos, params=Params())

Gaussian dot stimulus.

Parameters:c – contrast [0.0,1.0]

class stimuli.Pill(pos, params=Params())

Orientation circle stimulus. This Stimulus is useful as a response choice for orientation selection.

Parameters:

• th – size of stimulus
• R – radius
• d – width of orientation bar
• alpha – stimulus’ opacity (1.0 is opaque)

class stimuli.RDKMod(pos, params=Params())

Random Dot Cinematogram with modulated speed

Dots move together along axis controlled by “theta” parameter. Speed of each dot is controlled by

vx = a + b*cos(2*pi*f*cos(gamma)*x[0] + phi)

vy = a + b*cos(2*pi*f*sin(gamma)*y[0] + phi)

The speed is computed from the initial location (x[0],y[0]) of each dot. Then

R = rand-0.5

x[t+1] = x[t] + vx + vx*noise*R

y[t+1] = y[t] + vy + vy*noise*R

Parameters:

• width – width and height in pixels
• n – number of dots
• theta – motion direction in radians
• gamma – angle of modulation relative to the motion direction in radians
• a – speed modulation parameter a
• b – speed modulation parameter b
• f – speed modulation parameter f
• phi – speed modulation parameter phi
• tilt – tilt angle
• slant – slant angle

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