Describe the relationship between size of the receptive field and acuity or discriminative ability of the recetor?

The size of the receptive field varies inversly with acuity. So when you have a smaller receptive field, you have a greater acuity. For example, your finger tips vs your calf. Your fingertips can feel things a lot better than your calf can. This is because they have a smaller receptive field (ie dense grouping of receptors), and therefore can distinguish between many stimuli at a time. Whereas your calf is a large receptive field with non-dense receptors, and have smaller acuity.