Replication is an essential concept in psychological science. It can give rise to new insights into promising scientific developments, ensuring the quality and reliability of scientific research....Show moreReplication is an essential concept in psychological science. It can give rise to new insights into promising scientific developments, ensuring the quality and reliability of scientific research. Vagus nerve stimulation (VNS) showed that it can be deployed as an alternative treatment for patients suffering from drug-resistant depression and epilepsy. However, VNS is highly invasive and comes with great risks. The non-invasive transcutaneous VNS (tVNS) may induce this similar effect, by targeting the locus coeruleus-noradrenergic pathway (LC-NA). In the current study, we replicated the paper by Sharon et al. (2021), investigating the effect of tVNS on human pupil dilation. Throughout the experiment, the left ear of each participant was stimulated with the tVNS device, using short pulses of 3.4 seconds. Furthermore, pupillometry was deployed as a measure for pupil dilation. The outcome of this replication was in contrast with Sharon et al. (2021), as the results showed no significant difference between the tVNS and the sham condition. The final results might have been affected by the small sample size, the different adoption of materials, and an unequal ratio of males and females among participants. Future research should use a larger sample size, replicate more consistently and systematically, and adopt an equal ratio of gender. More research is necessary to establish reliable parameters for discoveries on the probable therapeutic effects of tVNS.Show less
Memory is complex and poorly understood. In this study we aim to measure the effects of arousal on long term memory using an established positional response paradigm often used in short-term memory...Show moreMemory is complex and poorly understood. In this study we aim to measure the effects of arousal on long term memory using an established positional response paradigm often used in short-term memory research. Using this paradigm, the relationship between arousal and the accuracy, confidence and precision of long-term memory was tested. The effect of sleep quality on the successful recall and precision of long-term memory was also tested. Sleep quality was measured using the Sleep Quality Scale (SQS). We introduced a state of arousal by promising a reward for correctly categorizing man-made or natural stimuli. Participants were shown these stimuli on the first day and given a surprise test after 24-hours. Performance was measured using the positional response paradigm. Afterwards they filled in the SQS with additional questions. Arousal was expected to increase the accuracy, confidence and precision of the recall of the stimuli in the rewarded condition. SQS scores were expected to correlate negatively with precision and accuracy. We found a significant effect of arousal on confidence and accuracy. There was no effect of arousal on the precision of long-term memory. This is likely due to the design of the experiment, as well as the small sample size. There was no significant effect of SQS scores on accuracy or precision, although trends were observed that support the original hypothesis. The results support the theory that arousal increases accuracy and confidence of long-term memory. Further research is needed to determine how arousal affects the precision of long-term memory.Show less
Memory performance is extremely susceptible to changes in the environment. Differentiating how individual factors affect memory and determining which neural circuits are involved in different parts...Show moreMemory performance is extremely susceptible to changes in the environment. Differentiating how individual factors affect memory and determining which neural circuits are involved in different parts of memory is very difficult because when memory is tested or consolidated, multiple brain regions and neural circuits are involved in these memory processes. In this study, we examined what effect arousal, specifically inducing reward anticipation during memory encoding would have on participants’ memory performance, when tested after a 24-hour delay. Participants were also asked to report on their sleep quality, in the interval between day 1 and day 2 of testing. The Sleep Quality Scale scores were compared with the participants’ overall memory performance in order to determine whether sleep had a beneficial effect on their memory. Memory performance was measured based off of three different components. We measured memory accuracy, memory confidence and memory precision in the memory test. Our results showed that reward anticipation does indeed modulate and enhance memory performance. However, within our sample, only memory accuracy and memory confidence were enhanced. Furthermore, we were unable to find a direct relationship between sleep on memory performance. Nevertheless, given that previous research has found evidence to suggest that sleep promotes better memory performance, we conclude that there were limitations in our study, and that ultimately sleep and reward anticipation do exert beneficial effects on memory performance. Nonetheless, to what extent, and which specific aspects of memory, i.e., memory encoding or memory consolidation are modulated by sleep and reward anticipation, has to be researched further.Show less
The impact of reward anticipation on the precision of long-term memory is important to study as further insights into how different factors affect different aspects of memory will guide us in...Show moreThe impact of reward anticipation on the precision of long-term memory is important to study as further insights into how different factors affect different aspects of memory will guide us in understanding illnesses associated with poor memory and help develop potential treatments. Thirteen healthy participants took part in a memory task in which memory accuracy, confidence, and precision were measured. Across a two day study, participants looked at objects and placed them in specific places on a computer screen based on whether or not the category of the objects was rewarded or not and performed a short number comparison task that indicated how much reward they would receive. Participants then came in on day two to do a surprise memory test on the objects seen on day 1. The also rated their confidence in that assessment, and indicated where on the screen they placed these objects. Reward anticipation was manipulated in order to non-invasively activate dopaminergic regions of the brain. We found that memory accuracy and confidence was significantly better for reward predicting objects, while memory precision was not. This study contributes to the current literature regarding reward anticipation and its effect on memory, but more research is required.Show less
Episodic memory is the ability to recall personal experiences within their associated context. Reward-related brain regions are found to influence episodic memory through dopaminergic...Show moreEpisodic memory is the ability to recall personal experiences within their associated context. Reward-related brain regions are found to influence episodic memory through dopaminergic neuromodulation. In this study, we manipulated arousal in reward-related areas of the brain through inducing a state of reward anticipation, with the aim to enhance dopaminergic activity. We investigated whether reward anticipation influenced the participant’s performance in a long-term memory test. Since memory appears to not be an allor-none concept, participants were not only tested for retrieval success, but also for memory precision – the retrieval of objective details of events. Long-term memory precision is considerably understudied in light of reward anticipation. Individual differences in reward sensitivity may influence the impact of reward-related brain regions on memory. Scoring high on optimism, as a core characteristic of extraversion, involves having a sensitive reward system – potentially heightening reactivity of the dopamine system. Participants were also tested for the personality construct optimism, which we expected to enhance the effect of reward anticipation on memory precision. Our results show that the state of reward anticipation leads to enhanced accuracy and confidence in memory retrieval, measured 24h later, however not memory precision. Thus, the present study is somewhat supportive of the dopaminergic memory consolidation theory, with optimism as a possible mediator for this relationship. We propose that further research is necessary to better understand the impact of reward anticipation on the specific precision aspect of long-term memory retrieval, and how optimism traits influence this process.Show less
