Validación del instrumento para la medición de la gestión del conocimiento

The broad implications of the present findings for the inhibitory models will be described in the conclusions section, after presenting experiments concerning directed forgetting. Here the specific discussion concerning the RIF effect only is presented. Three different inhibitory accounts of RIF were assessed in order to establish the locus of inhibitory effects in long-term memory. However, this locus has not been established as none of the tested models gained empirical support.

The most consistently refuted model is the pattern-suppression model developed by Anderson and Spellman (1995). According to this model, inhibition works to suppress features that belong to semantic representation of Rp- items. This account predicts that when such suppression occurs, it should be detectable with all types of cues that require access to conceptual representations of Rp- items. This prediction was consistently falsified in the present set of experiments. In

Experiments 1 and 2, category independent cues semantically related to multiple studied items were used to cue memory at test and no RIF was found. Experiments 2, 4, 7, and 8 used item-specific independent cues, with experiments 2, 4 and 8 employing cues semantically related to their targets and Experiment 7 employing cues which were only episodically related to their targets. In none of these

experiments was RIF obtained. Although some of these null results may stem from factors other than the use of independent cues at test per se, as in the case of Experiment 4 in which changes in encoding could have been responsible for abolishing RIF (a similar case could be made for the associated cue condition in Experiment 8), at least some of these null results (Experiments 2, 7 and the

unassociated cue condition of Experiment 8) were contrasted directly with reliable RIF obtained under the same encoding conditions with the procedural differences limited to using original rather than independent cues at test.

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Altogether, these results indicate that RIF does not occur due to changes in memory representations at the level of semantic features. It is important to add two additional notes to this conclusion. Firstly, the present results cannot be taken to imply that RIF never occurs with independent cues. Numerous experiments reported in the literature suggest that sometimes it does occur when memory is tested with such cues (Anderson, Green et al., 2000; Camp et al., 2005; Aslan et al., 2007). What has to be stressed, however, is that the pattern-suppression model of semantic inhibition predicts not that RIF may be present with independent cues under some conditions, but that this effect is generally cue-independent and this prediction is not supported by the present results. Secondly, these results cannot be taken to imply that inhibition in semantic memory never occurs. Norman et al.

(2007) in their model of RIF implemented an inhibitory mechanism that works both in episodic memory and in semantic memory in which inhibition leads to an

unbinding of semantic features constituting a single conceptual representation.

With the help of one of their simulations Norman et al. (2007) argued that

inhibition in semantic memory is necessary to account for the findings from the task that does not require use of episodic memory (Carter, 2004; as described in

Norman et al.; see also Johnson & Anderson, 2004). The present series of experiments used only tasks that involved episodic memory and thus these experiments cannot speak to the issue of semantic inhibition in semantic memory tasks. The present studies can only be taken to imply that inhibition at the level of semantic memory does not operate in episodic memory tasks.

If inhibition does not occur at the level of semantic features, then the proponents of this approach need to argue that the mechanism of inhibition operates in episodic memory to disrupt episodic links between different semantic representations. An inhibitory model of RIF developed by Norman et al. (2007) takes such an episodic perspective by describing how the mechanism of unlearning affects episodic links that tie semantic representations of Rp- items to other

semantic elements which may later be used as cues to retrieve these Rp- items.

Importantly, in order to account for the occasional finding of RIF with independent cues, this model makes an assumption of broad effects of unlearning and describes

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how episodic links for Rp- items that are not a direct source of competition during retrieval of Rp+ items become activated and disrupted. The predictions concerning this model were tested in Experiments 4 and 7, in which episodic links were created between independent cues and their targets. The model by Norman et al. predicts that if such episodic links become activated during retrieval practice of Rp+, they should be subjected to the operations of the inhibitory mechanism of unlearning. In Experiments 4 and 7 it was ensured that the activation of these links occurred by designing a procedure in which episodic links between independent cues and their targets were established in the main study phase. In this way context encoded for these associations matched context encoded for associations between original cues and Rp+ items. If participants use contextual cueing during retrieval of Rp+ items, then this cueing should lead to activation of independent cue-to-Rp- item

associations, as argued by Norman et al. However, in Experiments 4 and 7 no RIF was obtained. Although, again, the null finding from Experiment 4 could stem from the changes in the encoding session compared to the control Experiment 3, such a criticism does not apply to the findings of Experiment 7 in which the encoding phase was exactly the same as in the control Experiment 6 in which RIF was obtained with original cues. Altogether, these findings indicate that retrieval practice of Rp+ items does not disrupt all episodic links referring to semantic representations of Rp- items.

Finally, the last option for the locus of effects of an inhibitory mechanism is provided by the constrained episodic inhibition approach by which inhibition serves to disrupt an episodic link between an original cue and Rp- item. Although this idea seems to be inconsistent with the occasional findings of RIF with independent cues, it nevertheless has advocates in the published literature (e.g. Racsmány & Conway, 2006; Racsmány et al., 2012). The reason why the findings from independent cues cannot serve to refute this approach is that results obtained with independent cues are often inconsistent and can be criticized on the methodological basis.

Specifically, Camp et al. (2009) argued that in the independent cue methodology participants may use the strategy of covert cueing and use covertly retrieved original cues to search memory for Rp- and Nrp items. If inhibition affects episodic

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links between original cues and Rp- items, then the mechanism of covert cueing should lead to RIF even when only independent cues are presented at test. In Experiment 8 an attempt was made to test both the covert cueing explanation of findings of RIF with independent cues and the inhibitory hypothesis of disruption to original cue-to-Rp- item associations. Although the results indicated that covert cueing occurred when independent cues became associated with original cues in a separate phase of the experiment, no RIF emerged as a result of covert cueing.

These findings have two implications. Firstly, they suggest that covert cueing may not be responsible for occasional reports of RIF with independent cues. What is responsible for such results remains unknown. This problem could not have been effectively addressed with the present procedures because in none of the

experiments reported here was RIF with independent cues obtained.

Secondly, and more importantly for the present purpose, these results suggest that inhibition does not affect episodic associations between original cues and Rp- items. If participants used associations between original cues and their targets to retrieve the latter, even though they were provided only with

independent cues, and yet no RIF emerged, then it indicates that associations between original cues and Rp- items were as effective for cueing memory as

associations between original cues and Nrp items, which contradicts the predictions of the inhibitory account. A word of caution is warranted here, however, as this reasoning is crucially based on the assumption that participants used a covert cueing strategy. This assumption is partially supported by the observation that independent cues associated with original cues produced better memory

performance than unassociated independent cues. However, it can be also argued that this difference reflected encoding effects by which participants generated targets when presented with pairs of independent and original cues for study.

To summarize, three types of inhibitory frameworks for RIF were examined and none of them gained support from the present findings. The results concerning the pattern-suppression model and the model developed by Norman et al. (2007) seem quite strong as they directly contradict specific predictions formulated within these frameworks. The evidence concerning the constrained episodic inhibition

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model are of limited strength as they come from a single experiment in which the interpretation of results is dependent on the assumptions concerning the strategies employed by participants. However, it has to be stressed that the approach of searching for the locus of inhibitory effects in the retrieval practice paradigm that has been adopted here can be suboptimal for testing this particular inhibitory model. The constrained model suggests that inhibition operates at the level of original cue-to-Rp- item associations. On the other hand, an interference-based model, which constitutes the alternative to inhibitory approaches to RIF, places the locus of the mechanism responsible for RIF also at the level of original cue-to-Rp- item associations. If two competing theories place the locus of RIF at the same level of memory representation of Rp- items, then close scrutiny of this locus is unlikely to provide clear indication as to which of these theories is actually correct.

The idea that inhibition can be supported over interference-based accounts of forgetting in long-term memory by examining the locus of a mechanism

responsible for RIF comes from the work of Anderson and his colleagues (Anderson

& Bjork, 1994; Anderson & Spellman, 1995). In this work it has been argued that inhibition occurs at the level of semantic representations of suppressed items and thus the independent cue methodology can provide unequivocal evidence

supporting inhibitory model. However, the present findings contradict this notion and show that if inhibition occurs in the retrieval practice paradigm, it does not affect semantic representations. Instead, the present findings suggest that if inhibition does occur, then it works at the same level of episodic links as the

alternative mechanism of interference. In this scenario, considerations on the locus of inhibitory effect cannot provide strong evidence supporting this mechanism over the alternative model of interference.

If discovering the locus of the effects responsible for RIF is not sufficient to support the inhibitory approach over the interference-based framework, two research strategies may be used to provide further theoretical insights into mechanisms of forgetting in long-term memory. Other research paradigms can be used in which inhibition is contrasted with the alternative mechanisms or other differences between inhibition and interference may be discussed in the context of

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the retrieval practice paradigm. Focusing on the latter strategy, it is worth reiterating that multiple differences other than the locus of a mechanism of RIF have been described between inhibition and interference. The one that is relevant to the findings of the experiments reported here concerns the issue of the

competitiveness of retrieval practice. As described earlier, the inhibitory framework makes an explicit prediction that the magnitude of RIF should be related to the amount of competition exerted by Rp- items during retrieval of Rp+ items. Only when Rp- items compete for access during retrieval of Rp+ items, an inhibitory mechanism needs to be recruited to resolve interference (Anderson et al., 1994;

Anderson, 2003). In the present study the comparison of results of Experiments 5 and 6 brings the issue of competitive retrieval into focus. These experiments, which employed original cues at test, differed only in the conditions of the encoding of Rp+ items. In Experiment 5 these items were presented once with their original cue and in Experiment 6 they were additionally presented twice with their episodic item-specific independent cues. In both experiments Rp- and Nrp items were presented three times, once with original cues and twice with independent cues.

The RIF effect was obtained in Experiment 6 but not in Experiment 5. A potential explanation of this unexpected dissociation builds on the concept of competitive retrieval. It could be argued that when encoding of Rp+ items is impoverished relatively to encoding of Rp- items, as in Experiment 5, retrieval practice becomes too competitive and inhibition is no longer able to resolve interference. As

described by Norman et al. (2007), in this case to-be-inhibited episodic links become activated even before the relevant cue-to-Rp+ item links, which makes inhibition ineffective in regulating retrieval.

Although the comparison of Experiments 5 and 6 may suggest that

competitiveness of retrieval plays an important role in shaping the pattern of RIF, as the inhibitory frameworks would suggest, it is important to note that the results obtained in these experiments are actually in the opposite direction to the

straightforward predictions of an inhibitory account. These results suggest that RIF can be eliminated when retrieval competitiveness is increased, not that RIF is a monotonic function of competitiveness. The hypothesis that the relationship

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between competitiveness of retrieval practice and the magnitude of RIF is a non-monotonic one is not inconsistent with the inhibitory approach, but it is also not the one that can be formulated within this approach based on fundamental assumptions of this framework. There is nothing in the idea of inhibition that requires an assumption according to which inhibition stops working at a high level of competitiveness. Thus, although the present findings can certainly be considered in terms of an inhibitory framework, they should not necessarily be treated as empirical support for the inhibitory mechanism of RIF.

The other research strategy that can be used to further examine the inhibitory account of forgetting in long-term memory is to provide additional data from a different paradigm. If the inhibitory mechanism can account for the results in the retrieval practice paradigm only by postulating that inhibition works at same level of memory representation that is postulated also to be affected by an

alternative account of interference, then it is reasonable to examine a different paradigm in which inhibition is assumed to operate on a different level than the alternative account. The experiments on directed forgetting will be presented next to meet this aim. In directed forgetting studies, inhibition is contrasted not with a mechanism of interference but with the context change account that makes a very specific prediction, different from the predictions of the inhibitory framework, about the locus of the mechanism responsible for forgetting, as will be described next. Thus, the aim of the directed forgetting studies will be similar to the one reported for the retrieval practice paradigm, to examine which part of memory representation becomes affected in forgetting and by this to determine if inhibition can be a mechanism that leads to this impairment.