Final answer:
W. H. R. Rivers is usually cited as the founding figure in psychological research on acculturation, known for his work during the Torres Strait expedition that contributed to the development of psychological anthropology.
Step-by-step explanation:
The "father" of psychological research on acculturation is often considered to be W. H. R. Rivers, a British psychiatrist and anthropologist recognized for his pioneering work in this field. Rivers's significant contributions came from his studies during the Torres Strait Island expedition in 1898, where he examined the inheritance of sensory capabilities and disabilities among Melanesian populations. This research became influential as it challenged misconceptions of the time and placed importance on both biological inheritance and environmental influences on psychological development, illustrating that Melanesians had the same mental capacity as Europeans.
Rivers's work was pivotal in opening doors for future scholars within the realm of acculturation and the historical development of psychological anthropology. Although other researchers like John Schumann and George Herbert Mead have made substantial contributions to the field of psychology and the understanding of acculturation, it is Rivers who is often recognized as one of the major presences in the early movement of integrating cultural factors into psychological studies.