Figure 618

(a) Recall in the same versus different contexts, data from Godden and Baddeley (1975); (b) Recognition in the same versus different contexts. Data from Godden and Baddeley (1980).

Memory seems to depend jointly on the nature of the memory trace and the information available in the retrieval environment. The emphasis on the role played by contextual information in retrieval is also valuable. Contextual influences were ignored or de-emphasised prior to Tulving's encoding specificity principle, but there is strong evidence that recall and recognition are both affected greatly by the similarity of context at learning and at test.

There is a danger of circularity in applying the encoding specificity principle. Memory is said to depend on "informational overlap", but there is seldom any direct measure of that overlap. It is tempting to infer the amount of informational overlap from the level of memory performance, which produces completely circular reasoning.

Another serious problem associated with Tulving's theoretical position is his view that the information available at the time of retrieval is compared in a simple and direct fashion with the information stored in memory to ascertain the amount of informational overlap. This is implausible if one considers what happens if memory is tested by asking the question, "What did you do six days ago?" Most people answer such a question by engaging in a complex problem-solving strategy to reconstruct the relevant events. Tulving's approach has little to say about how retrieval operates under such circumstances.

A final limitation of Tulving's approach concerns context effects in memory. Tulving assumed that context affects recall and recognition in the same way, but that is not entirely true. Baddeley (1982) proposed a distinction between intrinsic context and extrinsic context. Intrinsic context has a direct impact on the meaning or significance of a to-be-remembered item (e.g., strawberry versus traffic as intrinsic context for the word "jam"), whereas extrinsic context (e.g., the room in which learning takes place) does not. According to Baddeley (1982), recall is affected by both intrinsic and extrinsic context, whereas recognition memory is affected only by intrinsic context.

Convincing evidence that extrinsic context has different effects on recall and recognition was obtained by Godden and Baddeley (1975, 1980). Godden and Baddeley (1975) asked participants to learn a list of words either on land or 20 feet underwater, and they were then given a test of free recall on land or underwater. Those who had learned on land recalled more on land, and those who learned underwater did better when tested underwater. Retention was about 50% higher when learning and recall took place in the same extrinsic context (see Figure 6.18). Godden and Baddeley (1980) carried out a very similar study, but using recognition instead of recall. Recognition memory was not affected by extrinsic context (see Figure 6.18).

Search of associative memory (SAM) model

Raaijmakers and Shiffrin (1981) put forward the search of associative memory (SAM) model. This model, which was developed further by Gillund and Shiffrin (1984), provides an account of recall and recognition. In part, it uses the notion of encoding specificity to develop a detailed mathematical model. Some of the main assumptions of the SAM model are as follows:

• The memory representations or traces formed for each presented item contain information about the item itself, about the learning context, and about other items in the list.

• In recognition memory, each test item plus context forms a compound that activates a memory representation; if that memory representation exceeds a familiarity criterion, the participant identifies the test item as having been presented before.

• In recall, the participant uses contextual information to search repeatedly through long-term memory using associations among items. Selected words that fit the correct context are identified as list words.

The SAM model explains many of the main findings. For example, encoding specificity is accounted for, because changes in context between study and test reduce recall and recognition. Recognition failure of recallable words can also be explained by the SAM model. Recall will be superior to recognition memory when the retrieval cues available at recall overlap more with the stored representations than do the retrievable cues available at recognition (Gillund & Shiffrin, 1984).

As Haberlandt (1999) pointed out, it is especially impressive when models can predict unexpected effects such as recall superiority to recognition. Raaijmakers (1993) showed that the SAM model can explain the part-list cueing effect. In this effect, participants who are given part of a list to assist recall of the remaining items find it harder to recall the remaining items than do participants not given this assistance. According to the SAM model, when the experimenter presents list items as cues, this disrupts the participants' normal search processes through long-term memory, and this inhibits access to the remaining list items.

Evaluation

The SAM model accounts for numerous findings relating to recall and recognition, including counterintuitive findings such as recall superiority to recognition and the part-list cueing effect. However, Roediger (1993) argued that the success of the SAM model is reduced because it contains a large number of assumptions, which makes it relatively easy to account for most phenomena. Roediger (1993) also argued that some of these assumptions are purely mathematical in nature, and may not be capable of being tested empirically.

Multiple-route approaches

Most approaches to recall and recognition (including the two-process and encoding specificity theories) are oversimplified. It has often been assumed that there is only one way in which recall occurs, and only one way in which recognition occurs. This is implausible, because it implies that memory operates in a rather inflexible way. In fact, various strategies can be used to recall or recognise stored information. Some of the flavour of these multiple-route approaches will be given here.

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