<span>The visual cliff is a laboratory device for testing <u>depth perception</u> in infants. This device is basically an apparatus that resembles a cliff, on top of which a child is placed so as to check its perception of depth from the cliff to the bottom of it. This is important so as to check whether the child has visual or motor problems. </span>
if you are talking about both then the first when measures the meters in a high tide and a low tide and the bottom one shows how it has been increasingly rising and lowering
