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Chapter 2: Research Methods in Cognition
www.ablongman.com/robinson-riegler
memory for high-frequency words and low-frequency words are nearly identical in height,
indicating equivalent performance.
Interactions. If you want to know whether these two independent variables influence
one each other, we need to look at the means for each of the four conditions created by
the factorial design. Take a look at Figure 2.4a, which shows the means for all four conditions in our hypothetical memory experiment. Looking at these means reveals that the
previously stated conclusions based on the main effects do not ring completely true.
This is because the data indicate a statistically significant interaction between the two
variables. When examined in isolation, the independent variable of word frequency
seems to have no influence on remembering; but when you look at the means for all
four conditions, this overall effect is quite misleading. The ability to remember high- and
low-frequency words depends critically on how memory is tested. High-frequency
words are remembered better in recall, while low-frequency words are remembered
better in recognition. In other words, there is an
interaction between the effects of memory test
and word frequency.
Memory Test
An interaction might be described as a “difrecall
recognition
ference
of differences.” In Figure 2.4a, it’s aphigh
44
60
Word
parent
that
this is exactly what we have. In recall,
Frequency
low
30
84
there is a 14% advantage for high-frequency
(a)
words; in recognition, the difference is reversed, with a 24% advantage for low-frequency
words. So the high-frequency/low-frequency
100
High frequency
difference is different for the two memory tests.
Low frequency
The same interaction can be viewed from a dif84
80
ferent angle. Compare memory for recognition
and recall. Recognition is superior to recall over60
60
all, but the superiority is much more evident in
the case of low-frequency words. Once again, we
44
40
see a difference between differences; the difference between recognition and recall is 54% for
30
low-frequency words but only 16% for high20
frequency words. So viewed either way, the effects of word frequency and memory test depend
0
Recall
Recognition
on each other. This interaction also emerges
from the bar graph in Figure 2.4b, which in(b)
cludes all four conditions. Compare the pattern
Figure 2.4 Hypothetical data showing an
observed in each half of this graph. In the reinteraction between word frequency and type of
call panel, the bar representing high-frequency
memory test, presented as a table and a bar graph.
words is higher than the bar representing memBoth displays reveal an obvious difference of differory for low-frequency words. The converse can
ences, with high-frequency words better recalled
be seen in the recognition panel, demonstratthan low-frequency words, and low-frequency words
ing the interactive effect of word frequency and
being better recognized than high-frequency words.
memory test.