Some of my earliest memories are of these kinds of perception, including the 'phosphenes' caused by internal pressure on the eyes when one looks to the side (th

Some of my earliest memories are of these kinds of perception, including the 'phosphenes' caused by internal pressure on the eyes when one looks to the side (they appear as fleeting, roundish flashes). It's curious to me that such formative memories would be triggered by something entirely 'internal' - not a measure of external stimulus involved. Perhaps in a similar way, someone else's earliest memory might be that of becoming aware of their heart beating!