Psychology2016

Memory 253

shorter study times of 30 minutes to an hour followed by short breaks (Cepeda et al.,
2006; Dempster & Farris, 1990; Donovan & Radosevich, 1999; Simon & Bjork, 2001).
to Learning Objective PIA.5.

Reasons We Forget

6.11 Identify some common reasons people forget things.

There are several reasons people forget things. We’ll examine three theories here.

ENCODING FAILURE One of the simplest is that some things never get encoded in the
first place. Your friend, for example, may have said something to you as he walked out
the door, and you may have heard him, but if you weren’t paying attention to what he
said, it would not get past sensory memory. This isn’t forgetting so much as it is encod-
ing failure, the failure to process information into memory. Researchers (Nickerson &
Adams, 1979) developed a test of long-term memory using images of a common object
for many people, a penny. Look at Figure 6. 8. Which view of a stop sign is the correct
one? People see stop signs nearly every day, but how many people actually look at them
that closely so the information is encoded into long-term memory?

encoding failure

failure to process information into

memory.

Figure 6.8 Stop!
Many people look at stop signs multiple times a day. Which of these stop signs is closest to an actual stop
sign? The answer can be found on the next page.

Interactive

The fact that this man can remember the

things shown in the pictures even after many

years makes it unlikely that the memory

trace decay theory can explain all forgetting

in long-term memory.

MEMORY TRACE DECAY THEORY One of the older theories of forgetting involves the
concept of a memory trace. A memory trace is some physical change in the brain, per-
haps in a neuron or in the activity between neurons, which occurs when a memory is
formed (Brown, 1958; Peterson & Peterson, 1959). Over time, if these traces are not used,
they may decay, fading into nothing. It would be similar to what happens when a num-
ber of people walk across a particular patch of grass, causing a path to appear in which
the grass is trampled down and perhaps turning brown. But if people stop using the
path, the grass grows back and the path disappears.
Forgetting in sensory memory and short-term memory seems easy to explain as
decay: Information that is not brought to attention in sensory memory or continuously
rehearsed in STM will fade away. But is decay a good explanation for forgetting from
long-term memory? When referring to LTM, decay theory is usually called disuse, and
the phrase “use it or lose it” takes on great meaning (Bjork & Bjork, 1992). Although
the fading of information from LTM through disuse sounds logical, there are many

memory trace

physical change in the brain that

occurs when a memory is formed.

decay

loss of memory due to the passage of

time, during which the memory trace

is not used.

disuse

another name for decay, assuming

that memories that are not used will

eventually decay and disappear.