What is reality? Hmmm. I'd say that the reality we experience is defined by a mix of external sensation and personal cognitive processes. Both of these will differ one person to the next as various peoples' sense organs have varying levels of efficacy, as do their cognitive processes. The ideal would be a mind and a set of eyes etc that present the outside universe as it actually is - this would be the objective reality.

Failing that, the easiest way to approach objective reality is what we might call the 'democratic' approach - look for sensations and experiences that are shared by as many people as possible, as presumably there must be some external basis to these.