Gibson and Walk Methodology

A strength of Gibson and Walk's research is that it was lab-based, and so there was a high degree of control over the variables. For example, as the setup of the visual cliff apparatus was precisely recorded (there was a board laid across a large sheet of heavy glass; the position of the patterned material; the placement of humans and non-human animals) means that it is highly reliable. Other researchers can repeat this experiment and obtain the same results. 

It could be argued that this study was high in internal validity, as the depths, type of patterned materials, reflections on the glass and types of non-human animals were controlled and provided variations in the findings. Therefore it does appear that Gibson and Walk were indeed measuring depth perception in humans and non-human animals, and were adding to our understanding. Indeed, this is supported by the evidence from the variations in results between dat old chicks and human infants for example. 

There was a range of different non-human animals from a range of different environments. For example the animals used were chicks, lambs, kids, rats, kittens, dark-reared kittens, pigs and aquatic turtles. This meant that Gibson and Walk had a wide variety of participants to compare findings, and…