First, let me just say that, while I tend to be knowledgeable on a wide variety of topics, I am absolutely atrocious with details such as names, times, and specific values. A friend of mine has decided that I'm imagining an effect that I have experienced on countless occasions and which I have seen documented on countless more. The effect in question specifically relates to the effect of intense reflected light on the human eye's ability to discern details in shadow while excluding the possibility of more than one primary source of light. For example, assume the following details to be true: you are outdoors it is a cloudless day with intense sunlight the time is no later than 2pm or earlier than 10am you are not at a latitude which would appreciably reduce the intensity of sunlight at mid-day as compared to the equator there are no primary sources of light other than the sun you are standing with the sun "behind you" (if it is morning you are facing west, if it is after noon you are facing east) the surfaces reflecting the light of the sun are not typically known for their reflectivity (grass, concrete, asphalt, dirt, bark, leaves, etc) a man with olive skin is standing in front of you with a hood over his head his hood is pulled low so that it casts a shadow over his face his hood is not low enough that his face is physically blocked from your sight you have just exited a building with no windows and whose only source of light was a fire in a fireplace, your eyes have had no time to adjust. The question is: given these details, would the average human being be able to make out the fine details of the hypothetical man's face well enough to recognize the individual later without the hood? I have argued quite adamantly that they would not be able to. Instead the intense sunlight reflected by every surface except his face would result in a silhouette effect for the hooded area making it impossible to make out the fine details of his face even with the ambient light that would inevitably reach it. I have personally been in the situation I described above and many more producing similar effects. I have also seen this effect portrayed in anime and live action fiction both with hoods and also just shadows cast on a person by a building... so I know others have experienced this as well (they must have to feel it necessary to portray it in their works of fiction). I have also seen this effect documented as part of separate research when I was working on trying to accurately reproduce real world effects of sunlight in a virtual 3D environment. Because of these things I am very very hesitant to even consider that I might be wrong about this... however, I have a standing policy of always making myself open to the possibility of such no matter how preposterous it seems. I have chosen to place the question here in biology because my friend has insisted quite vigorously that the effect I described is flat impossible due to the workings of the human eye... though he has not really expanded on why. He also acknowledges this effect is possible if the primary light source is directly behind the person but insists that it is impossible with reflected light... though personally I can not see where the fact that the light has been reflected is relevant. Only the over all amount of the light striking the retina seems relevant to me in that context. He has also rejected my comparison to the effect of a camera with a shutter speed set too low (causing over exposure to the areas of the scene with the most light and exaggerating the dark areas) though it seems to me that this is a one-to-one comparison for the purpose of the question outlined above. He specifically claims that, should the scene change, a human eye would update the image fresh with no "streaking" where a camera would blur (an effect used for time-lapse photography). This to him seems to be the main basis of why it would be different... though again I can see no relevance to the question above. Unfortunately, I can not think of any of the terminology involved in this phenomenon and thus have no way to research it and find the aforementioned documentation again. This has left me in the lurch so to speak between being unable to prove myself right and also unable to prove myself wrong. Any one care to help untangle this mess or perhaps toss some terminology my way so I can research it myself?