Hubel and Wiesel named cells in the visual cortex

Visual cortex

The visual cortex of the brain is the part of the cerebral cortex responsible for processing visual information. It is located in the occipital lobe, in the back of the brain....

 that exhibit end stopping properties Hypercomplex cells, but later research has found them to be subclasses of the simple

Simple cell

A simple cell in the primary visual cortex is a cell that responds primarily to oriented edges and gratings . These cells were discovered by Torsten Wiesel and David Hubel in the late 1950s ....

 and complex

Complex cell

Complex cells can be found in the primary visual cortex , the secondary visual cortex , and Brodmann area 19 .Like a simple cell, a complex cell will respond primarily to oriented edges and gratings, however it has a degree of spatial invariance. This means that its receptive field cannot be...

 cells. End stopping is when a cell's response increases as a stimulus, for example a bar, expands to fill the receptive field, and then responds less when the stimulus exceeds the size of the receptive field

Receptive field

The receptive field of a sensory neuron is a region of space in which the presence of a stimulus will alter the firing of that neuron. Receptive fields have been identified for neurons of the auditory system, the somatosensory system, and the visual system....

There are three classes of cells in V1:
Simple cells: “line detectors “and “edge detectors “
Complex cells detect orientation
Hypercomplex cells detect length