Via Mind Hacks, psychologist Norbert Schwartz gives a revealing answer when asked what nagging things he still doesn't understand about himself:
I don’t understand ... why I’m still fooled by incidental feelings. Some 25 years ago Jerry Clore and I studied how gloomy weather makes one’s whole life look bad – unless one becomes aware of the weather and attributes one’s gloomy mood to the gloomy sky, which eliminates the influence. You’d think I learned that lesson and now know how to deal with gloomy skies. I don’t, they still get me.
Schwartz claims that the tendency he describes can be counteracted, even though his own experience suggests otherwise. It's fascinating to hear him ask, in essence, "Why is it that my awareness of facts about human psychology does not automatically exempt me from those facts?" Or, in other words, "Why must I be bound to behave humanly simply because I am human?"
This attitude — not uncommon among behavioral scientists — is extended to its logical end in the tenets of transhumanism. Consider Michael Anissimov's notion that "It is a physical fact about our brains that the connections between stimuli and pleasure/displeasure are arbitrary and exist mostly for evolutionary reasons.... [W]e will eventually modify them if we wish, because the mind is not magical, it’s 'just' a machine."
If the psychological fact that gloomy weather makes for gloomy moods is meaningless and ought to be nonbinding, why not make it so that gloomy weather makes for cheery moods? Why, after all, shouldn't we reprogram ourselves so that gloomy weather makes us feel like we're eating ice cream, having sex, or riding across moonbeams on a unicorn fed by marshmallows? (One wonders how then a description of weather as 'gloomy' could retain any communicable meaning — how, indeed, a word like 'gloomy' could remain intelligible at all — but no matter, for of course these too are but disposable artifacts.)