Misinformation Effect
Memory and the Misinformation Effect
Contents
Why does the Misinformation Effect occur?
There is a general acceptance, supported by research, for the misinformation effect: The introduction of misleading postevent information will impair the memory of an original event (Toland, Hoffman & Loftus, 1991). However, although this phenomenon is well-established its interpretation is not. This debate about why the misinformation effect occurs relates to a fundamental issue about human memory - whether or not memory traces are permanently stored.
Two of the mechanisms which have been offered to explain the misinformation effect are: the alteration hypothesis and the coexistence hypothesis (Toland et al., 1991). Both hypotheses share the assumption …show more content…
that the presentation of misinformation interferes with the original memory (referred to as memory impairment) and that this creates the erroneous reports given. The difference is between the types of interference that occur and the conclusions drawn regarding retrieval of an original witnessed memory.
The Alteration Hypothesis
This hypothesis takes the view that the misleading information actually alters the original memory traces. Support for this hypothesis comes from the inability to recover original memories after being presented with misleading postevent information.
This is the interpretation adopted by Loftus and colleagues who propose that the misleading information "overwrites" or replaces the original information so that it becomes destroyed. This results in the suggested information becoming an inseparable part of the original event memory.
The Coexistence Hypothesis
This hypothesis takes the view that the original information and the misleading information coexist in memory. This means that the original information is still there but it becomes inaccessible. Support for this hypothesis comes from "successful attempts to recover the original information after exposure to misinformation has presumably altered that information in memory" (Toland et al., 1991, p.241).
Studies by Bekerian & Bowers (1983) and Christiaansen & Ochalek (1983) have supported this view.
Source misattribution has also been proposed as an explanation of how two memories can coexist (Toland et al., 1991). A confusion occurs between the source of the original information and the source of the subsequently received information. This results in the person reporting an inaccurate version of events because the misinformation memory trace is more recent and more salient in memory which explains why it could be mistakenly attributed to the original event.
McCloskey and Zaragoza
McCloskey & Zaragoza (1985) suggested that postevent misinformation had no effect on original event memory and that misinformation neither altered the original memory trace nor interfered with it so that it became inaccesible.
They claimed that the misinformation effect was not because of memory impairment but the result of a bias that existed in the standard testing procedure. Their argument was that this problem with the testing procedure creates a response bias and the possibility that subjects are being influenced by demand characteristics.
The repsonse bias is explained in terms of misinformation acceptance (subjects report the misinformation when the original information was never stored) which is not the result of a memory impairment.
To counteract these problems McCloskey & Zaragoza (1985) proposed a modified test in which a novel item was introduced. The modified test procedure followed the classical misinformation test procedure until the recognition test stage:
An item was observed (e.g. a hammer) and a postevent item was introduced (e.g. a screwdriver), but during the forced-choice recognition test a novel item (e.g. a wrench) was introduced. This novel item was neither presented originally nor presented during the postevent information phase. The novel item was, therefore, tested against the original event …show more content…
item.
McCloskey & Zaragoza (1985) argued that this modified test procedure would determine whether misinformation affects the subjects' original memorial representation.
If the misinformation impaired the subjects' ability to remember the original information, then misled subjects could not perform as well as the controls. However, if the misinformation has no effect on the original memory there would be no difference between control and misled conditions. The results of McCloskey and Zaragoza's experiments supported the latter hypothesis. They concluded that misinformation has no effect on memory.
After McCloskey and Zaragoza - Where to now?
This research of McCloskey & Zaragoza's (1985) has sparked much criticism especially because their results did not rule out the possibility that more subtle forms of impairment may be occurring. However, there has been a noticeable trend in current misinformation research towards designing experiments which avoided the pitfalls of the standard testing procedure they pointed out. These new studies also show an increased sensitivity towards possible memory impairment.
Tversky & Tuchin (1989) introduced still another modification to their experimental procedure. Using a "Yes/No" recognition test instead of a forced choice one they found evidence that misleading postevent information does interfere with original event memory. It was concluded that the differences between results from the standard versus modified testing procedures were because
subjects used different judgement methods.
Belli (1989) argued that McCloskey & Zaragoza's (1985) modified test was insensitive to detecting memory impairment because the postevent item was not offered as a retrieval alternative. The exclusion of this item prevented detection of other possible influences of postevent misinformation on the original event memory. Belli argued that misinformation acceptance involved no influence of misinformation on original memory and what should be being considered to explain the misinformation effect, to at least some degree, is the involvement of misinformation interference (this includes both memory impairment and source misattribution).
Using a "Yes/No" retrieval test, instead of a forced choice procedure, Belli (1989) asked questions about the original and novel items and managed to separate out the effects of demand characteristics, misinformation acceptance, and memory impairment (Toland et al., 1991).
Belli (1989) wanted to try and establish whether or not memory impairment was involved in the misinformation effect or whether it was purely the result of misinformation acceptance as McCloskey and Zaragoza (1985) had concluded. Evidence for genuine memory impairment was found. A reduced performance on the original item exceeded increased performance on the novel item.
"Experiments such as Belli's (1989), which eliminate the influence of demand characteristics, and allow the misinformation effect to be decomposed into misinformation acceptance and memory impairment may well lead to a better understanding of what underlies postevent distortion of recollection." (Toland et al., 1991, p.246).
Contents
Why does the Misinformation Effect occur?
There is a general acceptance, supported by research, for the misinformation effect: The introduction of misleading postevent information will impair the memory of an original event (Toland, Hoffman & Loftus, 1991). However, although this phenomenon is well-established its interpretation is not. This debate about why the misinformation effect occurs relates to a fundamental issue about human memory - whether or not memory traces are permanently stored.
Two of the mechanisms which have been offered to explain the misinformation effect are: the alteration hypothesis and the coexistence hypothesis (Toland et al., 1991). Both hypotheses share the assumption …show more content…
that the presentation of misinformation interferes with the original memory (referred to as memory impairment) and that this creates the erroneous reports given. The difference is between the types of interference that occur and the conclusions drawn regarding retrieval of an original witnessed memory.
The Alteration Hypothesis
This hypothesis takes the view that the misleading information actually alters the original memory traces. Support for this hypothesis comes from the inability to recover original memories after being presented with misleading postevent information.
This is the interpretation adopted by Loftus and colleagues who propose that the misleading information "overwrites" or replaces the original information so that it becomes destroyed. This results in the suggested information becoming an inseparable part of the original event memory.
The Coexistence Hypothesis
This hypothesis takes the view that the original information and the misleading information coexist in memory. This means that the original information is still there but it becomes inaccessible. Support for this hypothesis comes from "successful attempts to recover the original information after exposure to misinformation has presumably altered that information in memory" (Toland et al., 1991, p.241).
Studies by Bekerian & Bowers (1983) and Christiaansen & Ochalek (1983) have supported this view.
Source misattribution has also been proposed as an explanation of how two memories can coexist (Toland et al., 1991). A confusion occurs between the source of the original information and the source of the subsequently received information. This results in the person reporting an inaccurate version of events because the misinformation memory trace is more recent and more salient in memory which explains why it could be mistakenly attributed to the original event.
McCloskey and Zaragoza
McCloskey & Zaragoza (1985) suggested that postevent misinformation had no effect on original event memory and that misinformation neither altered the original memory trace nor interfered with it so that it became inaccesible.
They claimed that the misinformation effect was not because of memory impairment but the result of a bias that existed in the standard testing procedure. Their argument was that this problem with the testing procedure creates a response bias and the possibility that subjects are being influenced by demand characteristics.
The repsonse bias is explained in terms of misinformation acceptance (subjects report the misinformation when the original information was never stored) which is not the result of a memory impairment.
To counteract these problems McCloskey & Zaragoza (1985) proposed a modified test in which a novel item was introduced. The modified test procedure followed the classical misinformation test procedure until the recognition test stage:
An item was observed (e.g. a hammer) and a postevent item was introduced (e.g. a screwdriver), but during the forced-choice recognition test a novel item (e.g. a wrench) was introduced. This novel item was neither presented originally nor presented during the postevent information phase. The novel item was, therefore, tested against the original event …show more content…
item.
McCloskey & Zaragoza (1985) argued that this modified test procedure would determine whether misinformation affects the subjects' original memorial representation.
If the misinformation impaired the subjects' ability to remember the original information, then misled subjects could not perform as well as the controls. However, if the misinformation has no effect on the original memory there would be no difference between control and misled conditions. The results of McCloskey and Zaragoza's experiments supported the latter hypothesis. They concluded that misinformation has no effect on memory.
After McCloskey and Zaragoza - Where to now?
This research of McCloskey & Zaragoza's (1985) has sparked much criticism especially because their results did not rule out the possibility that more subtle forms of impairment may be occurring. However, there has been a noticeable trend in current misinformation research towards designing experiments which avoided the pitfalls of the standard testing procedure they pointed out. These new studies also show an increased sensitivity towards possible memory impairment.
Tversky & Tuchin (1989) introduced still another modification to their experimental procedure. Using a "Yes/No" recognition test instead of a forced choice one they found evidence that misleading postevent information does interfere with original event memory. It was concluded that the differences between results from the standard versus modified testing procedures were because
subjects used different judgement methods.
Belli (1989) argued that McCloskey & Zaragoza's (1985) modified test was insensitive to detecting memory impairment because the postevent item was not offered as a retrieval alternative. The exclusion of this item prevented detection of other possible influences of postevent misinformation on the original event memory. Belli argued that misinformation acceptance involved no influence of misinformation on original memory and what should be being considered to explain the misinformation effect, to at least some degree, is the involvement of misinformation interference (this includes both memory impairment and source misattribution).
Using a "Yes/No" retrieval test, instead of a forced choice procedure, Belli (1989) asked questions about the original and novel items and managed to separate out the effects of demand characteristics, misinformation acceptance, and memory impairment (Toland et al., 1991).
Belli (1989) wanted to try and establish whether or not memory impairment was involved in the misinformation effect or whether it was purely the result of misinformation acceptance as McCloskey and Zaragoza (1985) had concluded. Evidence for genuine memory impairment was found. A reduced performance on the original item exceeded increased performance on the novel item.
"Experiments such as Belli's (1989), which eliminate the influence of demand characteristics, and allow the misinformation effect to be decomposed into misinformation acceptance and memory impairment may well lead to a better understanding of what underlies postevent distortion of recollection." (Toland et al., 1991, p.246).