Analisis de la anatomia ctenidial de Pisidium chilense

Potential limitations and recommended adaptations of the design of the experimental task which span both Experiment One and Two will be discussed. This will be followed by a broader discussion of potential opportunities for development in this area of research.

4.3.3.1 The methodology, materials and paradigm

Firstly, with regards to the experimental stimuli, although the materials attempted to achieve a balance between gender, relationships and social and occupational roles, these factors were not considered in the analysis. Katz et al. (2004) discussed the importance of social and cultural context on perception of sarcasm, and report that men produce more sarcasm and are considered more sarcastic than women. Thus, it is possible that greater difficulty is observed decoding the sarcastic comments of women than men. Although gender was controlled in the creation of the stimuli in the present study, it would be useful to consider gender effects in future investigations in this area. In addition, in relation to irony more generally, Pexman and Olineck (2002b) found that occupational stereotypes influenced detection of ironic intent. Therefore, exploration of the perception of sarcasm in vignettes with characters of different implied social and occupational contexts could be an interesting development.

Secondly, something which was not rigorously controlled in this experiment was use of direct versus indirect sarcasm. Since comprehension of direct and indirect sarcasm did not appear to differ for people with head injury in Channon et al.’s (2005) study, the

current study incorporated both types, using mostly direct sarcasm. It would be useful in future, however, to further explore Channon et al.’s (2005) finding through further research, especially since indirect sarcasm has been associated with additional cognitive demands (Bucciarelli et al., 2003).

This study did, however, control for positive versus negative sarcasm as all the sarcastic experimental stimuli featured negative sarcasm, i.e. saying something positive to communicate something negative. This was selected as it is the more common form of sarcasm (Gibbs, 2000). However, it might be useful in future to also explore and test positive sarcasm, since positive sarcasm uses negative remarks which if misinterpreted, (i.e., the non-literal meaning was not identified and the literal negative meaning inferred) they could be perceived as highly critical and offensive.

Regarding the specific experimental paradigm used in the current study, the yes-no response methodology was utilised, as opposed to more complex methodologies such as those seen in the TASIT (McDonald et al., 2002) and paradigms developed for off-line research (e.g. Channon et al., 2005), as this more easily enabled assessment of on-line processing through RT data (as well as accuracy scores). In addition, this approach was chosen in order to minimise cognitive load, given that individuals with severe brain injuries and cognitive impairments would participate in the studies. However, there have been criticisms in the past towards experiments for which a simple yes or no response is required. For example, Channon et al. (2005) argue that these responses do not capture the subtle differences involved in the processing of the sarcastic comments. For example, as was the case in the current study, it was not clear what kind of error was made, i.e. was the sarcastic comment interpreted literally, or non-literally but incorrectly. As mentioned previously, Channon and colleagues reported that the errors made on the sarcastic material in their task represented some literal interpretations but mostly inadequate and inaccurate non-literal interpretations. Although this was not directly explored in the current study, anecdotally, comments from the TBI participants to the experimenter during the experiment indicated that many literal remarks were being interpreted non- literally, and it would have been helpful to investigate more rigorously the nature of these literal errors in particular. Future studies that ask participants to explain sarcastic or literal vignettes may provide more insight in this domain.

In relation to the measures of aggression, although the BPAQ is a well validated measure (Buss & Perry, 1992; Harris, 1995, 1997), and does distinguish between verbal and physical aggression, it does not assess other types of aggression. It might be useful in

future research to consider aggressive behaviour in terms of the impulsive-premeditated divide, using the Impulsive/Premeditated Aggression Score (IPAS; Stanford et al., 2003). Furthermore, as previously mentioned, more specific measures of indirect aggression, such as the Indirect Aggression Scale (Forrest et al., 2005), would also be a valuable addition.

Moreover, use of self-report measures has limitations, especially in brain injured individuals who may have limited insight into their difficulties (Manchester & Wood, 2001; Stuss et al., 1991). However, there are also limitations of the self-report

methodology for non-brain injured individuals in relation to concern regarding how one is perceived by others, exemplified by the social desirability bias (Fisher, 1993). This problem was overcome in the TBI group by obtaining data of observed aggressive behaviour (OAS-MNR), which was possible given the residential nature of the

rehabilitation setting. This would, however, not be a feasible tool for a non-clinical group. However, a proxy-report measure, perhaps completed by a family member, carer or friend, would be a valuable adjunct to a self-report measure in non-clinical samples as well, if that was feasible.

4.3.3.2 Opportunities for development

Suggestions for amendments and developments of the experimental task and analysis techniques have been made above. In terms of wider developments of this research, it would be a helpful development and natural way forward to consider not only the comprehension of sarcasm, but the spoken use of sarcasm by people with TBI, and how this links to displays of overt aggression. Since sarcasm is a socially acceptable way to communicate aggression, perhaps people who had a TBI and are more overtly aggressive, are unable to successfully generate sarcasm. No studies currently exist that explore the ability of such individuals to produce and appropriately use sarcasm.

The current study captured a reflection of all participants’ cognitive ability, including aspects of executive function, by use of the MoCA, which was used as a control variable in the analyses. However, further explicit links with executive function should be explored, using more detailed measures. Executive function has been implicated in the processing of sarcasm and pragmatics, (e.g. McDonald & Pearce, 1996; Pearce,

McDonald & Coltheart, 1998), and Miller et al.’s (2008) proposed hypothesis notes the importance of language in conjunction with executive skills in the modulation of

impulsive aggression. As has been highlighted throughout this discussion, executive function seems to play a key role in the modulation of aggression (Villemarette-Pittman, Stanford & Greve, 2002). Verbal working memory, in particular, seems central. This has been linked to behavioural control via internal verbal processes such as deductive

reasoning, reflection, rehearsal and self-instruction (Baddeley, Chincotta & Adlam, 2001; Gruber & Goschke, 2004). More in depth testing in this area may be important to

consider in future research of sarcasm and aggression.

In terms of methodology for future research, single case studies may be a valuable way forward for research in the TBI field. Alderman et al. (1999) raise issues with group level research in this clinical area due to the heterogeneity of the individuals, and they support single case methodology. Though it was not within the scope of the current research, this could have been useful to gain a more in depth analysis of the performance of some of the individuals with TBI.