Relational Psychophysics in Humans and Animals offers a comprehensive and integrated overview of the often fragmented field of psychophysics. It introduces key concepts in psychophysics and clearly summarises and illustrates the central issues through telling examples. It combines empirical research and theoretical approaches from general psychophysics, animal psychophysics and human-infant psychophysics, to create a systematic comparison of these three key areas. Through out, Viktor Sarris makes a strong case for more comparative psychophysical research across different species and across different stages of development. He presents original research and examines frame-of-reference models, behavioural psychophysics, developmental psychophysics, perceptual-cognitive psychophysics and evolutionary perspectives, to create an integrated framework for the direction of new research. The book will be an invaluable aid for researchers in the fields of perception and psychophysics.