SafeSpeed wrote:
mosis wrote:
I'm 40, and have perfect vision.
Even 'perfect' human vision has pretty severe limitations.
Peripheral vision is useful, certainly, but the resolution is VERY poor - try reading with it! Impossible! Often peripheral vision can altert us to road hazards - that's very important to safe driving. But many important clues to hazards will never be spotted by peripheral vision. Sometimes all you get is a shadow beyond a parked van to warn you of a pedestrian emerging. If you're checking the speedo at the time you WILL miss the clue.
This is a key point and the reason for my previous post on this thread. Visual cognition is a significant area of modern psycology. Huge strides have been made in understanding how we make sense of the physical world around us via our eyes and brain. It is a complicated area however and I don't pretend to be up to date (my degree is nearly a decade old) nor do I claim I was an expert back then.
Saying that one's peripheral vision is 'excellent' is meaningless. As Paul mentioned, 'foveal vision' extracts the most rich and detailed information on which to base our perception. I could link to many studies which characterise the role of foveal vision (eg
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3269513&dopt=Abstract but there is some research that is directly relevant here. Horey et al '03 reviewed some recent studies by Summala et al. I won't go on too much but these are the words of objective researchers, not a speed obsessed death merchant like me.
Summala et al. (1996; replicated by Summala, 1998) examined the impact of IVTs using a technique where drivers were forced to focus their visual attention on a location inside the vehicle (located at various eccentricities) and to rely on peripheral vision to maintain vehicle control (lane keeping). In general, lane keeping ability declined with increasing eccentricity, although experienced drivers showed impairments at only the greatest separations, suggesting that they were better able to make use of peripheral information for vehicle control than were their inexperienced (novice) counterparts. Using the same forced-peripheral technique, Summala et al. (1998) and Lamble et al. (1999) investigated how well drivers were able to detect and respond to critical hazards (i.e., a lead vehicle braking) while focusing visual attention away from the driving scene. In these studies, reaction times to the critical events increased markedly with display separation and did not improve with driver experience. Taken together, these studies suggest that although peripheral vision may be used to support vehicle control, it is not able to sufficiently support hazard awareness, which is better served by foveal vision. The findings presented by Summala and colleagues offer some support for the notion of separate focal and ambient visual channels (Previc, 1998; 2000). This distinction comprises part of the resources within the visual modality of the multiple resource model of task performance (Wickens, 2002). In this model, focal visual channel relies heavily (though not exclusively) on foveal vision in order to complete tasks that require the discrimination of fine details (e.g., reading). In contrast, ambient vision utilizes peripheral vision to large degree for tasks involving perception of orientation and ego-motion. Multiple resources models posit that tasks which share common resources along a given dimension (e.g., processing stage, perceptual modality, visual channel, processing code) will be time-shared less effectively than tasks which utilize separate resources. For example, a driver may use focal vision to read information presented on a road sign while at the same time use ambient vision to keep the vehicle within their lane, however would be unable to read gauge information presented in the instrument panel, as this would require focal vision. As Summala et al. (1996) demonstrated, ambient vision does have its limitations, with performance becoming degraded at greater eccentricities. Therefore, the introduction of visual in-vehicle information creates a new source of competition for focal resources which will impact not only the availability of these resources for the detection and identification of road hazards but, depending on the location of the display, may also affect the ability to use ambient vision for vehicle control. As such, the information access costs associated with display separation become an important consideration for both focal and ambient driving tasks.
This was mainly centered on in-vehicle-technologies but findings could be transferrable even if the effect is weaker. My point again is that we still don't know what impact increased speedo checks make on our task performance. Saying 'my peripheral (x-ray, heat ray etc) vision is excellent' refers to the eyes. Its opthalmology. But what we see doesn't stop at the eyes, the brain makes sense of the information, ask too much of it and performance degrades. This is psychology.