4. Justificaciones de las propuestas de reforma del Baremo
4.1 Primero: Criterios para la determinación de la responsabilidad
The aim of the present study was to investigate whether or not manual pointing at pictures’ locations during encoding could enhance source memory for picture-location associations in young and older adults. In line with our expectations, it was found that a pointing strategy (pointing to pictures locations) led to better source memory than a verbal strategy (naming the pictures’ locations) in young and older adults (Experiment 1). Second, our expectation that pointing during encoding would lead to better source memory than observation only in young and older adults was supported in Experiment 2. And as expected, older adults performed equally well as the young adults on the item memory test, but poorer on the source memory test. A surprising finding in Experiment 1 was that item memory performance was better in the pointing condition than in the naming condition. A possible explanation is that naming compared with pointing toward the locations of the pictures was more unnatural. Finding the right words describing the location might have distracted attention away from the encoding of the content of the picture, which resulted in fewer pictures recognized in the item memory test. Note though that this potential drawback of the naming condition could not explain why pointing led to better memory performance, as Experiment 2 demonstrated that pointing also had a beneficial effect compared with observation only.
The present findings are in line with the claim made by Glisky et al. (2001) that source memory performance depends on the conditions under which encoding occurs. Our results also suggest that a simple action such as pointing at a picture location can help the integration of the picture and its location in memory. This is also in line with the account of Kormi-Nouri and Nilsson (2001), who stated that enactment promotes episodic integration, because the action and object that is acted upon are encoded and stored as a single event, and therefore results in better episodic memory. In addition to findings from enactment research showing that enactment or passive action observation compared with a passive verbal condition enhances associative memory (Feyereisen, 2009), the present study also showed that self- produced action in the form of pointing gestures compared with self-produced verbal cues, can lead to superior source memory. This suggests that in the case of associating spatial contextual features to its content during encoding, self-performed pointing cues are superior to self-performed verbal cues.
According to the multimodal theory proposed by Engelkamp (1998), encoding information in more than one modality (for example, by vision and by enactment) can enhance learning. In line with this theory, a possible explanation for the enhanced memory
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performance for pointed items is that the act of pointing added a motoric memory code and enriched the learner’s representation for the picture-location associations. However, in contrast to enactment or pantomimic gestures, that can represent (simulate) specific perceptual and or salient features of learning material, the pointing gestures used in the present study were only specific for the location of the pictures and not for the content of the pictures. Still we found that the picture-location association was stronger for the pictures that participants pointed at during encoding than the pictures of which locations were named or passively observed, even though this action does not represent the content (meaning) of the pictures. This can be explained via attentional processes during encoding. A possible explanation is that the pictures that were pointed at, received more attention than those that were not pointed at (selection-for-action hypothesis, Allport, 1989). An alternative explanation is that pointing toward picture locations is an egocentric and body-based, manner of encoding, compared with observation only, which is a more allocentric and scene-based manner (Chum, et al., 2007), this might make the pictures and their locations more salient and distinctive, which makes them easier to remember later on.
Despite the fact that these explanations are plausible accounts for why pointing enhanced source memory performance in our study, they do not explain how this works, in terms of an underlying mechanism. We suggest that neuroscientific research might provide insight into such underlying mechanisms. Several brain imaging studies showed that objects that are only perceived are differently processed than objects we intend to act upon by systems guiding visual attention, namely the dorsal stream for “vision for action” (processing “where” and “how” information important for source memory) and the ventral stream for “vision for perception” (processing “what” information important for item memory; e.g., Boussaoud, di Pellegrino, & Wise, 1995; Goodale & Milner, 1992; Milner & Goodale 2008). Interestingly, a study by Khader, Burke, Bien, Ranganath, and Rösler (2005) showed a specific involvement of the parietal cortex (the projectory site of the dorsal stream) in source memory linking word pairs to locations, but not for linking word pairs with pictures of faces. In explaining our findings, we suggest that in the present study, the pointed pictures might have been processed via the dorsal stream and pictures of which locations were named or only observed via the ventral stream. Because evidence suggests that the parietal cortex might be specifically involved in source memory for locations (Khader et al., 2005), we suggest that this mechanism may also underlie the positive effect of self-produced pointing during the encoding of pictures and their locations. However, caution is required when using this explanation, because we did not use brain-imaging techniques to measure the involvement of the dorsal and ventral stream. Therefore, future research is needed to test this potential explanation by adding neuropsychological evidence to the present behavioral results to investigate the recruitment of the dorsal and ventral areas during encoding and retrieval of pointed compared with named pictures-location associations.
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A limitation of the present study is that one could argue that the beneficial effect of pointing might result from transfer appropriate processing (Morris, Bransford, & Franks, 1997) or encoding specificity (Tulving & Thomson, 1973). That is, the appropriateness and overlap of the conditions under which encoding and retrieval occur, can improve memory. All responses in the retrieval phase were made by finger tapping on the touchscreen but only the pictures in the pointing condition, not those in the naming or observation only condition, were tapped during encoding. This overlap in response type in the encoding and retrieval phase in the pointing condition could have enhanced item memory. However, it should be noted that with regard to source memory retrieval, although the response type overlapped with that in the pointing condition, the format of testing overlapped with the naming condition in Experiment 1, in the sense that participants had to choose a word determining the source (e.g., “left top”) that they named in the naming condition. In terms of transfer appropriate processing, naming the locations during encoding might have benefited the source memory test, because this test asked participants to choose from the exact words used during encoding in the naming condition. The finding that source memory in the pointing condition was better than in the naming conditions in both age groups in Experiment 1 is therefore even more striking.
A potential limitation of Experiment 2 is that response data of the observed pictures in the encoding phase, such as eye fixations, were not recorded, because that would change the experimental procedure too much. Therefore, we could not check whether participants attentively looked at the pictures in the observation only condition. However, participants were explicitly instructed to visually attend to all stimuli, and they had to attend to stimuli to be able to determine whether or not they had to point at pictures during encoding (e.g., point to the artificial pictures and only look at the natural pictures). Given that the accuracy during encoding of pointing (i.e., pointing at the items that should be pointed at) was high (young, M
= 99.41%, SD = .01; old, M = 98.81%, SD = .02) and the number of false responses (pointing at
pictures that should only be observed) was low (young, M = 0.33%, SD = 1.51; Old, M = 0.52%,
SD = 0.92), we can assume that participants paid close attention to all pictures during
encoding.
Another potential limitation for the present findings might be that pointing itself did not enhance source memory performance, but that the positioning of the hands near the stimuli during encoding was sufficient. Evidence shows that performance on all kinds of cognitive control tasks improves if stimuli are perceived near the hands, for example tasks targeting spatial attention (Reed, Grubb, & Steele, 2006), visual working memory (Cosman & Vecera. 2010; Tseng & Bridgeman, 2011), and executive functioning (Weidler & Abrams, 2014). These findings can be explained by the selection-for-action hypothesis (Allport, 1989), which proposes that action intentions toward objects increase attention for these objects compared with objects that people do not intend to act upon. It would be interesting for future research
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to conduct a series of experiments to find out whether hand position alone can enhance spatial source memory, as to the best of our knowledge, this has not been investigated yet. In addition, another interesting direction for future research would be to investigate whether mere motor planning, without the execution of the movement itself (e.g., through mental imagery), might be sufficient to add a motor code to the memory that can enhance subsequent memory performance, and whether the specifics of the motor plan matter (e.g., object-directed vs. another direction of movement). This would provide further insight into the mechanisms underlying the effects found in the present study.
Although further research is needed, our results suggest that pointing gestures at an object during encoding can provide a cue that helps to focus attention in a body-based (egocentric) manner, and consequently might assist in retrieving the object’s locations at a later stage. This means that in daily life, pointing at an object might be an effective strategy for remembering its location at a later point of time, which might be especially helpful for older people.