Light-from-above heuristic is the assumption that light often comes from above, which influences our perception of form in some situations.
The "light-from-above heuristic" is a concept in psychology that refers to the tendency for people to assume that light comes from above, and to use this assumption to interpret and make judgments about visual stimuli. This heuristic can affect how people perceive and interpret objects, shapes, and textures, and can influence their judgments about depth, distance, and surface properties.
For example, the light-from-above heuristic might lead someone to perceive a raised surface as a bump or hill, and a depressed surface as a hollow or valley. It might also influence how people perceive faces, by making them more likely to perceive features that are lit from above as protruding (e.g. the brow ridge) and features that are lit from below as receding (e.g. the underside of the nose).
The light-from-above heuristic has been studied extensively in cognitive psychology and has been found to be a powerful and pervasive influence on visual perception and judgment. It is thought to be an adaptive heuristic that reflects the statistical regularities of the natural environment, where light typically does come from above.