On Thu, 13 Jan 2005, Nate Nagel wrote:

> > Eyetracker research shows that observers' eyes "prime" on the
> > taillamps and react faster when a taillamp they're already paying
> > attention to gets 5x brighter, than they do when the taillamp stays
> > the same and another red light comes on in a different location. The
> > amount of difference is fairly well related to the distance between
> > the tail and brake functions, which means Volvo has got it wrong.

> just seems counterintuitive to me... would like to know how big of a
> deal it really is?

Not huge, but present and significant.

> http://www.po944.de/images/po944_37.htm
> shows both brake and taillights on, confirming pattern...
> http://jimweb.free.fr/photos944.html
> sure looks like the reflectors only are lit for parking lights,

Not so clear-cut from where I sit. This photo, from your 2nd link above,
looks like the unlit retroreflectors are being hit with the same
photoflash that's visible as white spot reflections in a vertical line
running downward from the hatch lock:

http://jimweb.free.fr/rear.jpg

Mm. Don't like what this does to your horizontal angles of taillamp
visibility, if your interpretation is correct, but I'm not yet convinced
that it is.

I can think of several ECE-spec vehicles that have a tail bulb behind the
retroreflector *and* a tail/brake bulb outboard of that. I've owned a few
of them myself, even.

DS