Psychology Essay

Prof. Hosie Psych 4080

Essay

1) On-center (on/off) receptive field flashing light in the center region increases the cell response. Flashing a bright light around the subregion inhibits the cell response. For an off-center (off/on) receptive field it is the opposite. It gets inhibition from a light in the center and increased cell response when light is flashed around the subregion.

2) The Retinal geniculate nucleus and Lateral geniculate nucleus both receive input from receptors. RGN cells receive information from rods, cones, bipolar, and amacrine cells. LGN is the relay center for visual pathway and receives information from the RGN. LGN has six layers, made up of a bottom layer of 4 m cells and a top layer of 2 p cells. Receptors give input to both the LGN and RGN cells after the signal has been processed by collector cells. Each cell responds best to spatial frequencies that match the receptive field size.

3) When looking at Mach bands it appears the color bands curve inward and each band slight less darker and gradient, but they’re solid. Each band reflects different amounts of light due to retinal eccentricity. Looking at the receptive field you will see that the center is on the left side in darkness, and the surround is hit with light. It is on-center so center surround antagonism occurs. There is a lower response in this receptive field so that causes the edges to be darker. The opposite happens in the opposite receptive field on the other side of the edge. This causes the band to appear much lighter in contrast to the other bands.

Receptive fields also play a role in the Hermann Grid illusion. There is an appearance of small/white grey shadows at the intersection of black bars. This is caused by lateral inhibition. The receptive field has more light falling on the inhibitory surround, a smaller portion