What does a Reichardt detector do?

What does a Reichardt detector do?

Background. Reichardt Detectors are hypothetical neural circuits postuated for how the brain can track motion. In a Reichard detector, a cell in the brain receives input from two receptors in the eye, call them A and B. The input from A is delayed.

How do Reichardt detectors assist with detecting motion?

In Reichardt’s motion detector (Hassenstein & Reichardt, 1956), this moving target generates two signals from each of two visual filters, one before it jumps and another after it has jumped. Signal strength depends upon both the target’s contrast and its match with the filters.

Does the Reichardt detector have a processing delay?

This detector circuit uses a delay in the fibre on the left, which allows it to be directionally selective—the detector fires only when motion is rightward.

Are Reichardt detectors direction sensitive?

It is also sensitive to a particular direction of motion based on the relative locations of the receptive fields of the input neurons. Due to the simplicity of the motion detector, it can be easily fooled.

What is aperture problem?

The aperture problem refers to the fact that the motion of a one-dimensional spatial structure, such as a bar or edge, cannot be determined unambiguously if it is viewed through a small aperture such that the ends of the stimulus are not visible.

What is motion coherence?

The coherent motion display contains a set of moving dots, a fixed proportion of which are moving in a coherent direction (e.g. 0° in the figure above, in gold), while the rest are randomly replotted. When this proportion (“coherence level”) is high, task difficulty is low.

How do humans detect motion?

In both vision and touch, the brain perceives objects in motion as they move across a sheet of sensor receptors. For touch, this is the set of receptors laid out in a grid across the skin; in vision, these receptors are in the retina. As we run our fingertip across a surface, nearby receptors are excited sequentially.

What is aperture problem in vision?

Thus, the component of the image velocity in the direction of the image intensity gradient at the image of a scene point is. We cannot, however, determine the component of the optical flow at right angles to this direction. This ambiguity is known as the aperture problem.

What do human eyes detect?

When light hits the retina (a light-sensitive layer of tissue at the back of the eye), special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.

What part of the brain detects movement?

One of the brain areas most involved in controlling these voluntary movements is the motor cortex. The motor cortex is located in the rear portion of the frontal lobe, just before the central sulcus (furrow) that separates the frontal lobe from the parietal lobe.

How does the brain solve the aperture problem?

Global motion detectors will only show stimulation of one motion. How does the brain solve this problem? We solve the aperture problem through parallel processing- perceiving everything at once and convergence which leads to larger receptive fields and more complex tuning.

Why does aperture problem occur?

The local motion information from a single neuron is inherently ambiguous with respect to the global motion. That is, many different motions on the retina could cause the same response in a single motion sensitive neuron with a small receptive field. This is called the aperture problem.

What causes motion parallax?

Motion parallax is a monocular depth cue arising from the relative velocities of objects moving across the retinae of a moving person. The term parallax refers to a change in position. Thus, motion parallax is a change in position caused by the movement of the viewer.

How do eyes see colour?

Light travels into the eye to the retina located on the back of the eye. The retina is covered with millions of light sensitive cells called rods and cones. When these cells detect light, they send signals to the brain. Cone cells help detect colors.

How do eyes detect motion?

Q: How does the human eye handle motion perception? Motion perception is handled in the retina as light-sensing cells convert light into electric pulses while the rods and cones of the retina sense motion. The brain then interprets this information.