We are used to registering the dulling effect of the post-industrial world on our senses—the multiple chemical smells in our nostrils, the sugar-fat-salt poisons of fast-food on our tongues, the overdose of light and colors from screens and signs; the constant noise, from earphones, engines, fans and myriad other sources, that physically degrades our hearing.
We are less used to thinking of our overall perceptive capabilities in that way, but consciousness can be seen as a collective sensory organ, the sum of what our body tells us and how our brain interprets the data.
And that overall sense is being dulled as well, by the broken-dam floodwaters of ceaseless over-the-top information in which, like victims of perceptual waterboarding, we are being drowned.
Look at the facts. We register, through our senses, 13 million bits of information every second.  Of those, we are consciously aware of one to three. Virtually every second of our waking life we take in a barrage of manmade information, mostly visual and aural: 34 gigabytes worth,  according to recent research at UC San Diego, equivalent to 100,000 words daily, or almost a quarter of Tolstoy's massive War and Peace.
Memory, of course, is at least as much a process of filtering as of remembering. The trouble is, we are conditioned to want to retain and act on information. When our senses and consciousness are deluged with far more data than we evolved to deal with, we run into trouble.
Next week: Information overload, space and time, and depression
Tor Nørretranders, The User Illusion: Cutting Consciousness Down to Size, VIking Press 1998