One of the most common stumbling blocks for observational representationalists is the value judgements for reflected lights. Due to their contextual surround, they are often recorded (and probably perceived) far, far lighter than they actually are. Here we can see a moving solid bar (yes, the perception of an oscillating gradation on the moving bar is merely a psychophysical response to the stimuli with its context). The value of the bar is equal to the lightest region of reflected light. Notice how dark the regions of the bar moving over the middle tone seem to be. That’s because the values found in the region of the reflected light are nowhere near as light as those observed in the middle-tone region of this form. Keep this in mind when adding/modeling reflected light into your form. A quick overshoot in that region can quickly diminish a strong representation of form.