Working memory resources

Dans le document The maintenance of cross-domain associations in working memory (Page 124-128)

MEMORY: HYPOTHESIS AND PREDICTIONS

4.2. Hypotheses and predictions

4.2.2. Working memory resources

It is generally agreed upon that attentional resources play a role within the

maintenance of information. According to some theories, attention is the main resource to maintain information (e.g., the embedded process model and the TBRS model) with verbal rehearsal that can make an additional contribution. According to other theories (e.g., the multi-component model), attention plays a subordinate role within maintenance processes.

Attention is nevertheless stated to be necessary to encode information (Allen et al., 2006), to coordinate the double task of maintenance and processing (Logie et al., 1990) or to filter out non-relevant information (Ueno, Allen, et al., 2011; Ueno, Mate, et al., 2011). According to the multi-component model, the main resources implied in maintenance activities still concern the domain-specific resources.

Our goal was to verify two main hypotheses. These concern the involvement of domain-general and domain-specific resources respectively. Regarding domain-general resources, we wanted first of all to verify whether these resources are indeed involved in the maintenance of cross-domain associations. Secondly, we wanted to test whether the

maintenance of cross-domain associations is more dependent on attentional resources than the maintenance of single features. This latter hypothesis was advanced by researchers who claimed that the features of an association were maintained separately and that attention was necessary to keep these features together. Without attention, the associations would fall apart in their constituent features. This conclusion had been suggested both for cross-domain (Elsley & Parmentier, 2009) as well as for within-domain visuo-spatial feature associations (Wheeler & Treisman, 2002). The study by Elsley and Parmentier (2009) is the only study on cross-domain associations investigating this topic. Although their results and interpretation seem plausible, we will in the present research project search for confirmation, because of a rather unexpected result. To recapitulate, their study showed that features presented integrated were maintained integrated when enough attention is available. When attentional availability was decreased due to an additional memory load, this integration seemed to fall apart. In the analysis of the response times, Elsley and Parmentier showed that in the no-load condition, recombined probes were responded to slower than exact probes (see Figure 4.3). This is indeed the typical result observed in case of an integrated maintenance. This difference in reaction time disappeared in the load condition, removing hence any indication of integrated maintenance. However, we have noticed that this disappearance occurs in an unexpected way.

The disappearance of the difference between the exact and recombined probes in the load

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condition is mainly due to a decrease of the response times for recombined probes in the load condition. If the associations fell apart under a load, this would result in longer response times for the exact probes in the load condition. This was apparently not the case. The results of the error scores followed a logical pattern, with the error scores for exact probes increasing in the load condition.

Figure 4.3: Result of the study of Elsley and Parmentier (2009). Intact = Exact probes.

© 2009 Taylor & Francis

The results of this study cannot be interpreted straightforwardly because this is the only study investigating the representations of cross-domain associations while manipulating attentional availability. We are thus obliged to return to the maintenance of within-domain feature associations in search of further evidence. Elsley and Parmentier (2009) described in their paper investigating cross-domain associations a study they executed on within-domain feature associations. They used a similar design as in their study on cross-domain associations to investigate the representations of shape-location and shape-color associations. Just like for cross-domain associations, they found that these associations fell apart under attentional load.

Unfortunately, we have not found any publication related to this study. This is particularly regretful because, first of all, it could give us more information about the pattern of results observed in their study on cross-domain feature associations and, secondly, the study goes at the encounter of the predominant hypothesis that the maintenance of within-domain feature associations does not particularly depend on attentional resources (e.g., Allen et al., 2006;

Johnson et al., 2008; Vergauwe, Langerock, et al., 2014). Evidence favoring this latter hypothesis, but more importantly disfavoring the hypothesis that associations fall apart when less attention is available was provided by Gajewski and Brockmole (2006). They showed that, in a condition with low attentional availability, participants still reported more often either the entire association or nothing, than only one of the features. Nevertheless, one has to be aware that the difference between the just mentioned studies and the studies by Elsley and

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Parmentier (2009) might as well be explained by the intentionality of the binding. The conclusions in the studies of Elsley and Parmentier were based on implicit binding, while other studies denying the particular role of attention were all based on explicit binding of the features. Thus, the assumption about the role of attention within the representation of feature associations requires clearly experimental verification as straightforward evidence is lacking for cross-domain associations.

We tested the hypothesis that the maintenance of cross-domain associations would be more dependent on attentional resources than the maintenance of single features. This test would also allow us to verify the more general hypothesis that the maintenance of cross-domain associations depends on attentional resources. This was done by manipulating the cognitive load of the processing task for the experiments described in the previous section on capacity limits (i.e., Experiments 1, 2 and 3). Experiment 1 compared the maintenance of cross-domain associations with the maintenance of single verbal or spatial features.

Experiment 2 and 3 compared an integrated and isolated presentation of a same number of verbal and spatial features. All experiments were performed in the presence of a processing task, for which we manipulated the cognitive load. We expected an increase in cognitive load to result in a decrease in span scores. This prediction was based on the general agreement of the involvement of attentional resources within maintenance activities. More importantly, we did not expect any differential effect of the manipulation of the cognitive load between cross-domain associations and single features. In Experiment 1, we expected the decrease rate as a function of cognitive load to be equal for cross-domain associations and for verbal and spatial single features. In Experiments 2 and 3, we expected the decrease rate for verbal and spatial features to be equal in the integrated and the isolated condition. These predictions were based on the majority of studies on the maintenance of visuo-spatial feature associations, showing no particular involvement of attention for the maintenance of features associations as compared to the maintenance of single features, as well as on our reticence concerning the conclusions of the study by Elsley and Parmentier (2009) on cross-domain associations.

Our second research goal was to test the involvement of domain-specific resources in the maintenance of cross-domain associations. As stated in chapter two, research on the involvement of domain-specific resources within the maintenance of feature associations has largely been left aside and most studies have especially concentrated on the additional implication of attentional resources (in comparison to the maintenance of single features).

However, it is important to know the ensemble of resources that plays a role in maintaining

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feature associations. First of all, knowledge about which resources are involved could provide insights concerning the representations of cross-domain associations in working memory. If it appears that only attentional resources are involved with a limited contribution of domain-specific resources, this would support the hypothesis that cross-domain feature associations are maintained integrated in a domain-general buffer and not as their constituent features in their respective specific buffers. If however it were to be the case that domain-specific verbal and visuo-spatial resources were highly involved in the maintenance of cross-domain associations, then this would cast a doubt on the interpretation that these associations are maintained as integrated objects. This would rather be in accordance with the hypothesis expressed by Wheeler and Treisman (2002) that domain-specific buffers exist to maintain information, with features being associated making use of attentional resources. Secondly, if one knows which resources the maintenance of these associations depend on, then one can try to limit forgetting by creating the ideal maintenance context.

An excellent paradigm to test the involvement of domain-specific resources in the maintenance of cross-domain associations is the selective interference paradigm. We

combined the maintenance of cross-domain associations with three different processing tasks:

a verbal, a spatial and a neutral task (Experiments 4 and 5). If the maintenance of cross-domain feature associations is dependent on cross-domain-specific resources, then we should observe lower memory performance for these cross-domain associations when combined with the verbal and spatial processing task as compared to the neutral processing task. We took advantage of this design to confirm the involvement of domain-general attentional resources.

This was done by manipulating the cognitive load of the three processing tasks in the same way. If the maintenance of cross-domain associations depends on attentional resources, then we should see for each of the three processing tasks a decrease in memory performance as cognitive load increases.

We predicted that over and above an attentional involvement, we would also observe the involvement of domain-specific verbal resources but not domain-specific visuo-spatial resources. This is what has been observed in the few studies that have explored this issue (Guérard et al., 2013; Morey, 2009; Morey et al., 2013). We have however stated before that the locus of the effect remained to be defined. If the involvement of domain-specific resources is limited to encoding, as was recently suggested by Li et al. (2014), then we should not observe any effect of our manipulation of the domain-specific resources. If on the other hand, domain-specific resources play a role within the maintenance of feature associations, then our

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manipulation of the domain-specific resources should result in lower recall scores for the cross-domain associations when combined with the verbal (or spatial) processing task.

Dans le document The maintenance of cross-domain associations in working memory (Page 124-128)