found that babies aged 6 weeks had a decreased heart rate when placed on a visual cliff compared to babies aged 7 months that whimpered and their heart rate increased, showing a fearful response
Fantz (1950)
placed a child in front of 2 stimuli and timed how long the child spent looking at the stimuli. Fantz argues that the longer the child looked at a particular stimulus, that shows the child preferred it more than the other
Blakemore and Cooper (1970)
can be used as a background research as it shows how dark rearing can influence visual perception
