Kliegel, M., Martin, M., McDaniel, M. A., & Einstein, G.
O. (2001). Varying the importance of a prospective memory task: Differential
effects across time- and event-based prospective memory. Memory, 9,
1-11.
Prospective memory involves being reminded of a
delayed intention in the midst of an ongoing task. Errors in prospective memory can involve
forgetting to enact the intention altogether or enacting the intention at the
wrong time. Monitoring a delayed
intention can also interfere with performance on the ongoing
activity.
In the present research, Kliegel et al.
investigated the role played by the relative importance that subjects assign to
the delayed intention and the ongoing task. It seems reasonable that if participants
assign more importance to enacting the intention, then prospective memory
performance should increase and performance on the ongoing task should
decrease. Alternatively, if
participants assign more importance to the ongoing task, prospective memory
performance should suffer, but performance on the ongoing task should
improve.
Kleigel et al. argued, however, that this
relationship should only hold to the degree that the prospective memory task
requires attentional resources.
Because past research has suggested that time based PM tasks require
considerable attentional resources, the authors predicted a robust importance
effect on time based PM tasks.
Because past research has suggested that event based prospective tasks
(at least the types used in the present article) require relatively few
attentional resources, the authors argued that the importance effect should be
muted in event based PM tasks.
Experiment
1
Experiment 1 tested these ideas
with a time based prospective memory task.
Methods
Experiment 1 investigated the importance of
importance on a time based PM task.
Participants rated words on a series of dimensions as their ongoing
activity. Each word appeared for
five seconds and the participant had to perform the rating during the time
allotted or it was counted as an error.
The PM task required them to press a red key on the keyboard every two
minutes. They were counted as
having made the response on time if they were within a five second window. There was another key they could press
to make a clock briefly appear on the computer screen so they could check the
time. Half of the participants were
told that the PM task was the more important of the two tasks (i.e. High
Importance Condition). The other
half were told that the word rating task was the more important of the two tasks
(i.e. Low Importance Condition).
Results
Participants in the high importance condition made
more on time responses than did participants in the low importance
condition. Participants in the high
importance condition checked the clock more often than those in the low
importance condition. This was especially true during the 30 seconds immediately
prior to the end of the two minute period.
There was also a difference between the two conditions in the 30-60
second time period. Overall error rates on the ongoing activity did not differ
between the two conditions, except for during the 30 seconds immediately prior
to the end of the two minute period, during which time participants in the high
importance condition made more errors (i.e. failed to provide a rating for the
word).
Experiment
2
Experiment 2 tested these ideas
with an event based prospective memory task. In addition, the authors tested the
proposition that event based PM tasks would be resource demanding by having half
the participants engage in the ongoing word rating task while under attentional
load.
Methods
The basic
setup of the experiment was the same with two exceptions. First, the experiment was modified in
order to be make the PM task an event based task. Participants were told to press the red
key every time they saw a particular word.
This PM target word appeared every two minutes in order to make the
timing similar to Experiment 1.
Second, half of the participants engaged in the ongoing task while their
attention was divided by an auditory digit monitoring task.
Results
With regard to PM accuracy, there was no
significant difference between the high importance and low importance groups,
and no significant effect of the divided attention manipulation. Accuracy on the
ongoing task was impaired in the high importance condition, but only when the
digit monitoring task was also being performed (i.e. Importance X Attention
interaction). They argued that this occurred because (1) the importance
instructions cause strategic monitoring on the part of subjects (even though it
is not in fact needed by the PM task) and (2) the digit monitoring task takes up
additional attentional capacity and (3) this impairs performance on the word
rating task. Participants in the high importance condition also made more errors
on the digit monitoring task.
The
Authors’ Discussion
The importance people assign to completing the
delayed intention in a PM task influences performance on the task. But this is only true for those PM tasks
that require attention. As such,
time based PM tasks were influenced by the importance manipulation, but event
based PM tasks were not.