We already know that attention
is a limited resource, and we can't focus on everything
in our environment at once. But how do we filter out
the unimportant information, and how do we
decide when to shift our attention to something new? You've probably
experienced that even when you're in a loud
crowded room, you're pretty good at attending
to the one person who's talking to you. But you still hear bits
and pieces of conversations that you're not
trying to attend to. What those bits and
pieces are and aren't are what interest psychologists
who study selective attention, or your ability to focus
on something that's relevant to the task
at hand while ignoring other information. One way to study
selective attention is to observe
people while they're doing something called
a shadowing task. In this task, you're wearing
a pair of headphones, but different
information is coming in through each ear piece. So through the left ear,
you're hearing one thing, and through the
right ear, you're hearing something
completely different, maybe a different
person's voice, maybe a different
language, even. And you're told to
repeat everything that's said into one ear,
say, your right ear, so you have to pay attention
to it and to ignore the other. Based on what we learn about the
type of unattended information that we actually do and
don't end up comprehending, we can then learn more about
how selective attention works. And there are three
major theories that try to explain
this process. I'm going to talk about
these theories in terms of auditory attention,
but the same idea applies to other senses as well. The first is Broadbent's
early selection theory. Broadbent's idea was
that all the information in your environment goes into
your sensory register, which briefly registers or stores
all the sensory input you get. This includes words, clicks,
sirens, any input at all. Then this input gets transferred
to the selective filter right away, which
identifies what it's supposed to be attending
to via basic physical characteristics. So if we're talking
about language, the selective filter identifies
the voice, pitch, speed, accent, basic things like
that, that you don't really need to understand
in order to identify. Everything else
gets filtered out, and the selected
information gets moved along so that perceptual
processes can occur. These processes assign
meaning to the information. So while the selective
filter identifies the pitch of the one you
want to pay attention to, the perceptual
processes identify it as your friend's voice and
assign meaning to the words. Then you can engage in
other cognitive processes, such as deciding how to respond. Broadbent's theory
was a good start, but there are some problems. If you completely filter out
the unattended information before it gets assigned
meaning, then you shouldn't be able to
identify your own name when it's spoken in an
unattended ear. But as you've
probably experienced, you immediately perk up
when you hear your own name, even when it's across the room
and you haven't been paying attention to that
conversation before. This is known as the
cocktail party effect, and this, among other
things, led to researchers coming up with a new theory. A couple folks named
Deutsch & Deutsch proposed a late selection theory,
which moved Broadbent's selective filter to after
the perceptual processes. This means that you actually
do register and assign everything meaning, but
then your selective filter decides what to pass on to
your conscious awareness. That sounds pretty
good, but keep in mind that all this has to
happen really quickly. Given the limited
resource of attention, and the fact that we know our
brains are super-efficient, it seems a little wasteful to
spend all that effort assigning meaning to stuff
you won't ever need. So the answer may be somewhere
in between early selection and late selection. So we come to Treisman's
attenuation theory of selective attention. Treisman said that instead
of a complete filter, we have something
called an attenuator. Attenuate just means to weaken. So the attenuator weakens but
doesn't eliminate the input from the unattended ear. Then some of it gets through
to the perceptual processes. So we still assign meaning to
stuff in the unattended ear. It's just not as high priority. At this point, if you realize
that the unattended stuff is actually important, then you'll
switch over your attention and attenuate what you were
previously listening to. Later experiments suggested
that the difficulty of the task you're attending
to can affect when filtering occurs and how long it takes. The bottom line is there's still
some debate about which theory is the absolute best. But these three theories
have been pivotal in our understanding
of selective attention. It's important to
consider because attention is crucial to any other
cognitive function we perform. If infants weren't able
to attend a human voices and filter out birds
chirping or dogs barking, it'd be nearly impossible
to learn to speak. And if we didn't have
some way to refocus on to unattended
information, then we'd never notice if a car was
coming straight for us or if someone yelled fire. So now, hopefully, you have
a little better understanding of the theories that try to
explain this important process.