Question: What particular research by Ernst Weber are you interested in?

Matthew Longo answered on 8 Mar 2019:

There are very few laws in psychology, but “Weber’s law” is one of them. Weber showed that the amount by which two stimuli need to differ for someone to tell them apart increases in proportion to the magnitude of the stimuli themselves. This holds true over a remarkably wide range of sensory modalities and types of stimuli.

But the observation of Weber’s that is most relevant to my own work is what is now sometimes called “Weber’s illusion”. Weber found that as he moved the two points of a compass (the kind you draw circles with) across his skin it felt to him like the distance between them increased as he moved them from a region of relatively low sensitivity (e.g., the forearm) to a region of higher sensitivity (e.g., the palm of the hand). Weber seems to have just noted this informally from playing around on himself, but it’s easy to demonstrate that this illusion holds up in the lab.

You may have come across the famous illustration of the so-called “Penfield homunculus”, which depicts the ways in which some body parts (e.g., the fingers and lips) take up more space in the tactile part of the brain (the somatosensory cortex). The homunculus is distorted, with giant fingers and lips, and a tiny little torso. It makes sense that the brain would devote a disproportionate share of its resources to really sensitive body parts. What fascinates me about Weber’s illusion is that it suggests that the distortions that we see in textbook illustrations of the homunculus also affect our conscious perception of the world.