is the process by which our senses gather information and send it to the
brain. A large amount of information is being sensed at any one time
such as room temperature, brightness of the lights, someone talking, a
distant train, or the smell of perfume. With all this information
coming into our senses, the majority of our world never gets recognized.
We don't notice radio waves, x-rays, or the microscopic parasites crawling
on our skin. We don't sense all the odors around us or taste every
individual spice in our gourmet dinner. We only sense those things we
are able too since we don't have the sense of smell like a bloodhound or the
sense of sight like a hawk; our thresholds are different from these animals
and often even from each other.
absolute threshold is the point where something becomes noticeable to our
senses. It is the softest sound we can hear or the slightest touch we
can feel. Anything less than this goes unnoticed. The absolute
threshold is therefore the point at which a stimuli goes from undetectable
to detectable to our senses.
a stimulus becomes detectable to us, how do we recognize if this stimulus
changes. When we notice the sound of the radio in the other room, how
do we notice when it becomes louder. It's conceivable that someone
could be turning it up so slightly that the difference is undetectable.
The difference threshold is the amount of change needed for us to recognize
that a change has occurred. This change is referred to as the Just
difference is not absolute, however. Imagine holding a five pound
weight and one pound was added. Most of us would notice this
difference. But what if we were holding a fifty pound weight?
Would we notice if another pound were added? The reason many of us
would not is because the change required to detect a difference has to
represent a percentage. In the first scenario, one pound would
increase the weight by 20%, in the second, that same weight would add only
an additional 2%. This theory, named after its original observer, is
referred to as Weber's
you ever been in a crowded room with lots of people talking?
Situations like that can make it difficult to focus on any particular
stimulus, like the conversation we are having with a friend. We are
often faced with the daunting task of focusing our attention on certain
things while at the same time attempting to ignore the flood of information
entering our senses. When we do this, we are making a determination as
to what is important to sense and what is background noise. This
concept is referred to as signal detection because we attempt detect what we
want to focus on and ignore or minimize everything else.
last concept refers to stimuli which has become redundant or remains
unchanged for an extended period of time. Ever wonder why we notice
certain smells or sounds right away and then after a while they fade into
the background? Once we adapt to the perfume or the ticking of the
clock, we stop recognizing it. This process of becoming less sensitive
to unchanging stimulus is referred to as sensory adaptation, after all, if
it doesn't change, why do we need to constantly sense it?