Saylor URL: http://www.saylor.org/books Saylor.org
teaspoon of sugar will make a big difference in taste. But if you added that same teaspoon to a
cup of coffee that already had 5 teaspoons of sugar in it, then you probably wouldn’t taste the
difference as much (in fact, according to Weber’s law, you would have to add 5 more teaspoons
to make the same difference in taste).
One interesting application of Weber’s law is in our everyday shopping behavior. Our tendency
to perceive cost differences between products is dependent not only on the amount of money we
will spend or save, but also on the amount of money saved relative to the price of the purchase. I
would venture to say that if you were about to buy a soda or candy bar in a convenience store
and the price of the items ranged from $1 to $3, you would think that the $3 item cost “a lot
more” than the $1 item. But now imagine that you were comparing between two music systems,
one that cost $397 and one that cost $399. Probably you would think that the cost of the two
systems was “about the same,” even though buying the cheaper one would still save you $2.
Research Focus: Influence without Awareness
If you study Figure 4.5 "Absolute Threshold", you will see that the absolute threshold is the point where we become
aware of a faint stimulus. After that point, we say that the stimulus is conscious because we can accurately report on
its existence (or its nonexistence) better than 50% of the time. But can subliminal stimuli (events that occur below the
absolute threshold and of which we are not conscious) have an influence on our behavior?