“Why
distinctive information reduces false memories: Evidence for both impoverished
relational-encoding and distinctiveness heuristic accounts,” Hege & Dodson, 2004
Introduction
Studying
pictures or saying words aloud has been shown to reduce false-recognition rates
in DRM and repetition-lag paradigms. Two
mechanisms have been proposed:
(1) Distinctiveness heuristic: retrieval strategy where
the absence of memory for expected information is taken as evidence for an
event’s nonoccurrence
(2) Impoverished relational-encoding
account:
studying distinctive information interferes with the encoding of relational
associative information
Distinctiveness
heuristic argues that decreased rates of false-recognition/recall are due to
active suppression of the acceptance of critical lures based on a lack of
specific information, while the impoverished relational-encoding account argues
that the memorial information (familiarity) never comes to mind when presented
with critical lures due to a lack of associative relations acquired during
study. This study combined recall and
recognition tests to examine if either of the above mechanisms is in dominant
or exclusively at work, or if both play a roll in decreased rates of false
recognition/recall in the DRM paradigm.
Experimenters
contrasted word encoding vs. picture encoding using a free recall test format
using inclusion instructions (present both words you remembered studying and
any others that come to mind) and a follow-up recognition test where the S’s
checked those words they remembered as studied.
The predicted effects of the distinctiveness heuristic were that there
would be more false recall and false recognition as the inclusion instructions
disable the need for the employment of the retrieval strategy in question. The impoverished relational-encoding account,
in contrast, argues that false recognition and recall will be unaffected by the
instructions, and will remain lower than those in the former condition.
Methods:
42
S’s (16F, 26M) were shown a set of 72 pictures or 72 words that matched the
pictures. They were told they would hear
the words read over headphones, and either shown the word on a computer screen
or see a picture of it. At recall, they
were told to write down as many words from the list as they could remember and
any other words that came to mind. After
recall, they were asked to put a check mark next to each of the words they
remembered as being studied rather than just came to mind.
Results:
1. Recall rates for targets
were comparable between conditions.
2. There was a sharp decrease
in critical lure recall in the picture-encoding condition compared to word
encoding, supporting the impoverished relational-encoding account
3. More noncritical intrusions
occurred in word-encoding group than in picture-encoding group.
4. Recognition of targets was
comparable between conditions.
5. Picture-encoding condition
falsely recognized fewer critical lures.
6. False-recognition of
noncritical intrusions was comparable between conditions.
Overall,
these results support the impoverished relational-encoding account, but not
distinctiveness heuristic.
In
Experiment 2, picture-encoding and word-encoding were again contrasted, as well
as giving subjects either inclusion instructions (report studied items and
other items that come to mind) or standard instructions (only report studied
items). Distinctiveness heuristic
predicts, (1) analyses of recall rates of critical lures should show an
interaction between encoding condition and retrieval condition; (2) smaller
proportion of critical lures will be recognized in picture-encoding condition
compared to word-encoding. Impoverished
relational-encoding account additionally predicts that target recall rates will
be lower for standard instruction than inclusion instructions in word-encoding
condition but not in picture-encoding condition
Methods:
84
S’s (58F, 26M) were given either standard instructions or inclusion
instructions and shown either pictures or words naming the pictures. Materials were the same as in Experiment
1. Differences between instructions were
that standard instructions S’s were not told to recall any other words that
came to mind. Like before, after recall
S’s checked those words they felt had been presented during study phase.
Results:
1. S’s who studied words
reported more targets under inclusion instructions than standard.
2. S’s who studied pictures
reported targets at similar rates between instruction conditions, a pattern
predicted by impoverished relational-encoding account.
3. More critical lures produced
by S’s who studied words than those who studied pictures.
4. More critical lures were
reported under inclusion instructions than standard instructions.
5. Reporting rates for
noncritical intrusions were comparable between retrieval conditions and between
encoding conditions.
6. Endorsement rates for
Experiment 2 were higher overall than in Experiment 1 for both critical lures
and targets, though this was non-significant (p<0.07).
7. False recognition of
critical lures was lower for picture-encoding group than word-encoding group.
8. Recognition of targets was
comparable between encoding conditions.
9. False recognition of
noncritical intrusions was similar between encoding conditions.
Predictions
of impoverished relational-encoding account were supported by results in that
production rates for critical lures were lower in the picture-encoding
condition than word-encoding, and that inclusion instructions caused higher
rates of target recall in word-encoding condition but not in picture-encoding
condition. Distinctiveness heuristic was
supported, however, as there was a decreased rate of false-recognition in
picture-encoding condition than in word-encoding condition. The distinctiveness heuristic predicts that
recall of critical lures is through active suppression of responses, though the
word may come to mind, based on an the absence of
specifically detailed memory for the word.
Inclusion instructions were predicted to undo this effect as there would
not be a need for this retrieval strategy.
Results showed, however, that this effect did not occur. Instead, it
seems that the relational information is simply not encoded during study of
pictures while it is during study of words.
The authors suggested that the DRM paradigm may not be a good tool for testing
retrieval strategies, and are in favor of repetition lag paradigm studies as
these enable the unambiguous assessment of retrieval strategies through
responding made under time constraints.