Donald David Hoffman (born December 29, 1955) is an American cognitive psychologist and popular science author. He is a professor emeritus in the Department of Cognitive Sciences at the University of California, Irvine.

Hoffman studies consciousness, visual perception, and evolutionary psychology using mathematical models and psychophysical experiments. His research subjects include facial attractiveness, the recognition of shape, the perception of motion and color, the evolution of perception, and the mind–body problem. He has co-authored two technical books; Observer Mechanics: A Formal Theory of Perception (1989) offers a theory of consciousness and its relationship to physics; Automotive Lighting and Human Vision (2005) applies vision science to vehicle lighting. His book Visual Intelligence: How We Create What We See (1998) presents the modern science of visual perception to a broad audience.

His 2015 TED Talk, "Do we see reality as it is?" argues that our perceptions have evolved to hide reality from us. He followed this up with a book in 2019, The Case Against Reality: How Evolution Hid the Truth from Our Eyes.

Hoffman received a Bachelor of Arts degree in quantitative psychology from the University of California at Los Angeles (UCLA) in 1978, and earned his Doctorate of Philosophy in computational psychology at the Massachusetts Institute of Technology (MIT) in 1983 under David Marr and Whitman Richards. He was briefly a Research Scientist at the Artificial Intelligence Laboratory of MIT, and then became an assistant professor at the University of California at Irvine (UCI) in 1983. He has remained on the faculty of UCI since then, with a sabbatical during the 1995-1996 academic year at the Zentrum für Interdisziplinäre Forschung of Bielefeld University.

Hoffman has been married twice, secondly to Geralyn Souza.^{[citation needed]}

Hoffman notes that the commonly held view that brain activity causes conscious experience has, so far, proved to be intractable in terms of scientific explanation. Hoffman proposes a solution to the hard problem of consciousness by adopting the converse view that consciousness causes brain activity and, in fact, creates all objects and properties of the physical world. To this end, Hoffman has developed and combined two theories: the "multimodal user interface" (MUI) theory of perception and "conscious realism".

MUI theory states that "perceptual experiences do not match or approximate properties of the objective world, but instead provide a simplified, species-specific, user interface to that world." Hoffman argues that conscious beings have not evolved to perceive the world as it actually is, but have evolved to perceive the world in a way that maximizes "fitness payoffs". Hoffman uses the metaphor of a computer's desktop environment and its icons – the icons of a computer desktop provide a functional interface so that the user does not have to deal with the underlying programming and electronics in order to use the computer efficiently. Similarly, objects that human beings perceive in time and space are metaphorical icons that act as their interface to the world and enable them to function as efficiently as possible without having to deal with the overwhelming amount of data underlying reality. This theory implies epiphysicalism; i.e., physical objects, such as quarks and brains and stars, are constructed by conscious agents but such physical objects have no causal power. While panpsychism claims that rocks, mountains, the moon, etc. are conscious, "Conscious Realism" in this theory (Multimodal user interface theory) does not. Instead, what it claims is all such objects are icons within the user interface of a conscious agent, but that does not entail the claim that the objects themselves are conscious.

The interface theory of perception is the theory that human beings' perceptual experiences don't necessarily map onto what exists in the reality of itself. This is in contrast to the popular view of critical realism, which argues that some of their perceptual experiences map onto the reality of the natural world. In the critical realist's view, primary qualities like height and weight represent actual qualities of reality, whereas secondary qualities don't. Within the interface theory of perception, neither primary nor secondary qualities necessarily map onto reality.