comparing loftus and palmer and grant et al Flashcards
THE TOPIC
Effects between versus during encoding
and retrieval
The studies by Loftus and Palmer and Grant et al. are both
about cognitive psychology, specifically about the extent
to which our memory produces an inevitable and accurate
record of the material encoded: both found that it does not.
However, Loftus and Palmer looked at the disrupting effect
of information received between encoding and retrieval (in
the form of leading questions), and Grant et al. looked at the
disrupting (or enhancing) effects of the environment during
the processes of encoding and retrieval (specifically if they
matched or not).
THE RESEARCH METHOD AND DESIGN
Experiments using an independent
measures design
Although both studies were experiments using an independent
measures design there were some differences, for example in
the level of control. In Loftus & Palmer’s study the films were
of fixed durations for all participants, whereas reading time
could differ in the Grant et al. study. The two studies were
similar in that manipulation of the IV was achieved at the
testing stage, in Loftus and Palmer by asking leading or non-
leading questions and in Grant et al. by testing in matching
or mismatching environments. However, in Grant et al. the
environment in which the participants were tested was not as
well controlled, as although each student experimenter had an
identical tape of the background noise, they played it to their
participants through their own tape player and headset.
SAMPLING TECHNIQUE AND THE SAMPLE
Opportunity sampling and student
participants
The sample sizes were similar (Loftus and Palmer: 45 in
Experiment 1, 150 in Experiment 2; Grant et al: 39) and were probably similar in composition, Loftus and Palmer having
used all students, and Grant et al. having used acquaintances
of students. Both therefore used opportunity sampling, a non-
representative method, so the samples would, to an extent, have
had limited generalisibility. However, cognitive processes such
as memory are likely to be similar across a wide range of people.
EXPERIMENTAL MATERIALS AND
MEASUREMENT OF THE DV
Ecological validity, mundane realism and
quantitative data
For the main experimental stimuli, Loftus and Palmer used
driver education films from the Seattle Police Department and
Grant et al. used a published paper by Hales, both of which
were real-world materials relevant to the study. The mundane
realism of the studies was also similar in that both gathered
data for the DV using simplistic questioning (short answer
or closed questions) producing quantitative data, which only
partly represents real-world questioning of witnesses and
exam candidates. Overall, however, both studies lack ecological
validity in some respects as the emotion and motivation
of the participants would have been different from those
experiencing real car crashes or sitting exams.
APPLICATIONS
Courtroom versus classroom
The topics of both studies have obvious applicability to
real-world settings, in the courtroom and the classroom, both
suggesting that traditionally accepted behaviour (the use of
leading questions and revising in a noisy environment) could
be improved. While Loftus and Palmer’s findings have already
made an impact on the judicial system, the more recent
findings of Grant et al. have yet to have an influence. This
may be in part because the consequences of this research are
less important – it is not a social and moral question of the
innocent being convicted or the guilty going free, but a matter of individual choice about study habits. Furthermore, there is
no counterargument for any ‘benefits’ from the use of leading
questions, whereas students might justifiably doubt how
long they could motivate themselves to work in silence or the
possibility of doing so in a noisy hall of residence or home.
KEY THEME: MEMORY
Prior to Loftus and Palmer’s study, it was known that memories
were imperfect – they could be influenced – but this study
provided one of the earliest insights into the effects of post-event
information. It showed, by the combination of experiments 1
and 2, that the changes in memory that occurred as a result of
leading questions were due to the reconstruction of memory
rather than any other process. This has led to not only a
considerable field of research into eyewitness testimony but also
to practical changes in the legal system.
Grant et al.’s study has explored a different area of memory,
that of context-dependency, again an area that aims to explain
why our memories are less accurate in some situations
than others. Unlike Loftus and Palmer, prior research had
demonstrated clearly some factors affecting cue dependency,
and a range of theories had been proposed to explain these.
Grant et al.’s research differed because it explored the
importance of the factor of meaningfulness, and did so in the
realistic context of university study. Various aspects of the
source-monitoring hypothesis suggest that meaningfulness
may matter to eyewitnesses. For example, it has been
shown that central information is better at directing source-
monitoring than peripheral information, and that unfamiliar
source information is more often misattributed. Such evidence
implies that witnesses who comprehend the situation may be
able to produce more accurate testimonies than those who are
confused, e.g. because they do not know what is happening or
are frightened.
