In order to understand how we take in visual stimuli as we shop, it is first important to understand the different types of vision within our visual field. As these types of vision work together to produce our visual perception, and the transition between them is smooth, it is difficult to establish definitive boundaries between them and there are conflicting definitions of the terms, but below is a brief summary of our visual field.
Foveal vision refers to vision in the very centre of this field, where acuity is at its highest, and is approximately 2-3°wide. It is this vision that we use for fine processing of details. Our central visual field then expands out to about 60° in diameter and includes the parafoveal region, with parafoveal information used to determine where to move the eyes. Also included within this 60° diameter is our near peripheral vision, with everything outside of it being our mid and far peripheral vision. For simplicity, I will refer to our visual field in terms of foveal, parafoveal and peripheral vision throughout this post.
As distance from the fovea increases visual acuity drops off sharply, meaning our ability to take in detailed information decreases significantly. At even just ten degrees to the side of the point of fixation we can only resolve approximately one-tenth of the detail contained. We also lose our ability to detect colour and in our periphery are almost colour blind.