Abstract Neurons in the anterior regions of the banks of the superior temporal sulcus (STSa) of the macaque mon- key respond to the sight of biologically significant stimuli such as faces, bodies and their motion. In this study the responses of STSa neurons were recorded during the gradual occlusion of the experimenter and other mobile objects behind screens at distances of 0.5–4 m from the monkeys. The experimenter or other object remained out of sight for 3–15 s before emerging back in to view. We describe a population of neurons (n=33) showing increased activity during the occlusion of objects that was main- tained for up to 11 s following complete occlusion (when only the occluder itself was visible). This increase in activity was selective for the position of the occlusion within the testing room. Many neurons showed little or no change in activity prior to occlusion when the object or experimenter was completely in view. By coding for the presence and location of recently occluded objects, these responses may contribute to the perceptual capacity for object permanence. Keywords Macaque monkey · Object permanence · High-level visual processing · Superior temporal sulcus · Ventral stream Introduction “Existence constancy” (Bower 1967) or “object perma- nence” (Baillargeon 1993), “the experience that objects persist through space and time despite the fact that their presence in the visual field may be discontinuous” (Butterworth 1991), has been studied behaviourally in many species. Adult birds, cats, dogs and non-human primates all exhibit object permanence (for review, see Doré and Dumas 1987). At a basic level, adults of all these species will search for an object that has recently become occluded from sight. Such behaviour is evident neither in the young of these animals nor in human infants (for reviews, see Bower 1982; Baillargeon 1993), and the development of object permanence has been studied extensively. The capacity for object permanence may depend on the ability to distinguish between the visual cues present on disappearance that are associated with permanent objects and those that are not (Michotte 1950). Such cues may be learned during development. For example, objects do not generally suddenly “blink off” and disappear – this is more likely to be associated with object destruction (e.g. the bursting of a bubble). Michotte (1950) and Gibson (1979; Gibson et al. 1969) have described the visual cues that lead to object permanence. One of the most effective cues is that of gradual occlusion (produced, for example, when an object moves behind a screen). Gradual occlusion can lead to a strong impression of object permanence even when the observer knows that there is no permanent object present (Michotte 1950; Gibson et al. 1969), such as when the display is produced on a computer screen. Despite extensive behavioural and perceptual studies of object permanence, little is known about the neural mechanisms underlying the perception of objects under- going occlusion. In the present study, we examined the responses of neurons in the banks of the anterior superior temporal sulcus (STSa; Fig. 1a) of the macaque during and following the gradual occlusion of visual objects. C.I. Baker · C. Keysers · T. Jellema · B. Wicker · D.I. Perrett ( ✉ ) School of Psychology, University of St Andrews, St Andrews, Fife KY16 9JU, UK e-mail: dp@st-and.ac.uk Tel.: +44-1334-463044, Fax: +44-1334-463042 Present addresses: C.I. Baker, Center for the Neural Basis of Cognition, Carnegie Mellon University, 115 Mellon Institute, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA C. Keysers, Istituto di Fisiologia Umana, Universita di Parma, 43100 Parma, Italy T. Jellema, Psychological Laboratory, Helmholtz Research Institute, Utrecht University, 3584 CS Utrecht, The Netherlands B. Wicker, INSERM U 280, 151 Cours Albert Thomas 69424, Lyon cedex 03, France Exp Brain Res (2001) 140:375–381 DOI 10.1007/s002210100828 RESEARCH NOTE C. I. Baker · C. Keysers · T. Jellema · B. Wicker D. I. Perrett Neuronal representation of disappearing and hidden objects in temporal cortex of the macaque Received: 1 March 2001 / Accepted: 6 June 2001 / Published online: 31 July 2001 © Springer-Verlag 2001