Following Maloney (2008) we can say that evaluating the length of the lines relative to one another (or the continuity of the stick in water) is introducing a different level of cognition, beyond mere perception itself. The mind accurately percieves sense data from the physical world, but can potentially make errors in processing or analyzing that perception. This narrower definition of what perception is may diverge a bit from how most psychologists normally use the term, but that does not automatically invalidate the distinction.

Following Maloney (2018) we can say that evaluating the length of the lines relative to one another (or the continuity of the stick in water) is introducing a different level of cognition, beyond mere perception itself. The mind accurately percieves sense data from the physical world, but can potentially make errors in processing or analyzing that perception. This narrower definition of what perception is may diverge a bit from how most psychologists normally use the term, but that does not automatically invalidate the distinction.