Cue-picture time intervals

Cue-picture (S1-S2) time interval is an important factor because a negative slow wave, Contingent Negative Variation (CNV), develops during this time interval when that time interval is longer than 2 or more seconds (Poli et al., 2007; Van Boxtel & Brunia, 1994). CNV consists of at least two waves: early and late. Early waves are considered linked to the properties of the S1 and late waves to the S2. Late waves are named as Stimulus-Preceding Negativity and are associated with expectancy, motor preparation (Loveless & Sanford, 1974a,b) and emotional anticipation (Chwilla & Brunia, 1991). The cue-picture time interval in the current project was 3000ms, and this selection was made on the basis of a number of studies on anticipation (Poli et al., 2007; Walker, O’Connor, & Schaefer, 2011). Considering the presence of these early and late slow waves, current ERP data was broken down into two big time windows: ~0-1000ms for the study of early slow wave linked to cues, (S1) and 1000-3000ms for the study of late wave or SPN. In all the three current ERP studies, SPN a component for the anticipation of emotional valence was statistically non- significant. These findings cannot be interpreted, as the participants did not anticipate negative stimuli. These findings might be because the SPN is influenced by a shorter or longer S1-S2 time interval. Since this time interval was constant in all the studies, therefore, this factor cannot be ruled out. It is, therefore, difficult to make any conclusion regarding the relationship between anticipation of emotionally negative stimuli and SPN.

195 would be a viable option for future research to further probe the relation between anticipation and emotional memory.

8.7 Future Directions

The field of emotional memory is relatively young, and studies regarding the role of anticipation in enhancing or impairing emotional memory are still in its infancy. However, there are a large number of compelling directions for future research. An initial attempt has been made through this project to remove the inconsistencies in the methodology and the processes associated with anticipation of emotional memories. However, this project is not the final word on this issue. Rather, it is just a beginning of a new research avenue.

Future research needs to examine more closely the links between anticipation, emotion and memory. A number of possible future studies using the same experimental setup can be designed. Slight differences can be made between the studies to fine-tune analysis, and drill down to any differences seen. Further, the effects already manipulated, including Ps- Dm, encoding, emotional valence, or ERP, can be further studied to determine causal relations between the components. Other changes made can include showing participants more emotionally salient images, and more acutely manipulating their emotional response to images, and then testing their memory encoding and anticipation. Since only females were used in these studies, it would be important to bring in male subjects, as well as other age groups, to better understand any effects.

Other sources of stimuli may be used, including video, which may be found to have a greater impact on emotional manipulation than static images would. Further, auditory stimuli may be used as well, to create a more emotional environment. Many individuals can be affected emotionally via music, and using that may be beneficial in these studies. Providing subjects with short stories that are emotionally salient may be another avenue of research that can be found to be worthwhile variations of the studies in this thesis.

One thing that was strongly felt during the project was that the anticipation in response to cues was not as strong as it should be. In other words, there is the possibility that the cue might not capture and maintain anticipatory attention, for the anticipation was not made by the participants themselves rather just in response to the cue presented to them. Future research on anticipation and emotion memory may focus on designing a paradigm in which prediction or anticipation is made by the participants themselves, without cues. This design might help in reducing the cognitive load of the perception of extra stimuli and cognitive

196 processing such as working memory or discrimination processes. Moreover, this study design makes more sense as in the real life situation anticipation does not come with some discrete cues rather just as a perception of the situation.

This project has thrown up many questions that are in need of further investigation. For example, how do different cue types influence the brain waves related to emotion and memory? The findings of the current project revealed that valence and arousal of the to-be anticipated stimuli matters. However, it is unknown if the arousal and valence of the cue stimuli also produce some effects on memory.

How is the Contingent Negative Variation (CNV) influenced by different cue types: pictorial and verbal, and does it relates to memory and emotion in anyway? It may be determined that the cue type, beyond its emotional valence, does have an effect on memory encoding. Perhaps some individuals are more affected by visual cues, and others by verbal cues. The relationship between the ERP component of the Stimulus-Preceding Negativity (SPN) and emotional anticipation and memory needs to also be further investigated. Does the SPN have a relationship to emotionally negative images if a quick response to pictures is required? What happens to the emotional memory when the cues are not congruent to the pictures anticipated? It could be that an individual may better remember incongruences because they do not match up with expectations. This would make sense as part of adaptability is recognizing how previous experience relates to current or future ones.

Research on anticipation and emotion memory should take into account the individual differences while exploring this issue, some of which are discussed below.

i. Tolerance of uncertainty is another variable that might affect the relation between emotion and memory, especially in those contexts where uncertainty is involved. For instance, if participants are expecting something under non-informative or temporally unpredictable anticipatory condition, the findings might be confounded by the individual difference in the tolerance of uncertainty.

ii. Individuals also differ in their use of emotion regulation strategies, which differently influence brain activity at the pre- and post-stimulus phases. Findings of the current research suggest that anticipation itself can be used as an emotional regulation strategy. This conclusion was made on the basis that, without explicit instruction, participants tend to respond less to emotionally negative stimuli. Individuals habitually and predominantly use one emotion regulation strategy greater than the other while dealing with the

197 emotional stimuli. In the current investigation, no measure of emotion regulation was done by participants.

iii. However, a recent pupillary response study found a reappraisal strategy positively correlated with the high pupillary response at pre and post anticipatory phases compared to an expressive suppression strategy (Vandekerckhove et al., 2012). Future research may additionally measure the emotion regulation strategies used by participants to test the influence of anticipation and emotional memory formation. In one study, participants were asked to regulate their emotions in response to informative visual cues. Participants reduced negativity as a result of anticipation however in the current research and many others, with explicit instruction regarding regulation of emotion, individuals tend to down- regulate their emotion (Galli, Griffiths, & Otten, 2014). Further, it may be useful to produce an experimental design that compares implicit (without instruction) and explicit (specific instruction) emotion regulation strategies.

iv. Future research can be conducted to test the plausibility of whether anticipation can be learnt as a skill and if training in anticipatory skill can enhance our ability to detect negative emotions in others and to control our negative emotional state. A training program in anticipatory skill development might be used in some domains. The clinician and psychotherapist can use this skill training for therapeutic purposes while sports psychologist may use it to better help the athlete in cognitive control and emotion regulation during a tough situation.

8.8 Implications

Research into anticipation and its relationship to emotion and memory has several implications in the real world. From the biological perspective, emotions are psychological mechanisms that are evolved to solve adaptive problems, such as escaping from danger and predators, finding food, mates, shelter and protection, and being accepted and appreciated by other members of the species. Understanding of the underlying neurobiological routes and processes involved in forming emotional memories have been practically applied to understanding memory distribution in affective disorders of emotion. Specifically, research into emotion and memory has previously been applied to help develop therapeutic techniques to treat disorders of emotional memory such as phobias, and in treatment of post-traumatic stress disorder (PSTD). The studies presented in this project are important as they have added to the understanding of emotional memories and provided new knowledge that can be incorporated into, or used to guide future therapies for emotional disorders.

198 Anticipatory processes have been linked to the emotional disturbances in many psychiatric disorders, particularly the negative symptoms of anhedonia in schizophrenia patients, who show impairment in foresight in daily life (Eack & Keshavan, 2008). In laboratory settings, disturbances in anticipation have been correlated with reaction time and antisaccade and different anticipatory tasks (Avila et al., 2006; Fuller and Jahanshahi, 1999; Quintana et al., 2004). Further understanding of the scope and neural correlates of anticipatory behaviour and deficits may help explain several aspects of maladaptive functioning in schizophrenia. This understanding can be used to devise treatment plans and therapeutic interventions for these patients.

Few psychiatric disorders such as depression, anxiety and post-traumatic stress disorder exhibit a severe impairment in memory and emotion regulation. An understanding of the interaction between anticipation and emotion may help in enhancing the use of emotion regulation strategies. Anticipatory brain activity influences the encoding of emotional events, and this activity can be modulated by regulation of emotions (Galli, Griffiths, & Otten, 2012). Participants use different emotion regulation strategies such as reappraisal, avoidance and detachment, etc. In everyday life or in a lab setting, regulation of emotion before the occurrence of an aversive event might help reduce the impact of the negative event on memory.

Understanding of the anticipatory system may help in developing brain-computer interfaces (BCI). Anticipatory behaviour is, by definition, the prediction of future events and the value those events have on the current behaviour of an individual. Therefore, developing a computer system that utilizes algorithms that relate to anticipated behaviours may be beneficial in helping to better design robots used by those with lost or paralyzed limbs. Anticipation is expressed through consequences. Further work on anticipation might help devising a model of agent-environment interactions in which anticipation-related brain waves can be used to control devices such as a robot (Bozinovski & Bozinovska, 2004). 8.9 Concluding remarks

The greatest motivation for this thesis came from the theory, predicated on changes observed in pre-stimulus ERP activity, that anticipation leads to preparation, which increases processing efficiency- which in turn facilitates memory encoding (Park and Rugg 2010; Galli, Wolpe et al. 2011). In contrast, data from another study revealed that this pre- stimulus Dm effect can also be observed where no opportunity for preparation exists (Yick, Buratto & Schaefer, 2015). This led us to predict that memory related ERPs at the anticipatory phase might reflect the random fluctuation in attention rather than