Facial Fear Processing and Attention

Description
In this study, the role of attention in facial expression processing is investigated, especially as it relates to fearful facial expressions compared to happy facial expressions. Facial fear processing plays a critical role in human social interactions and survival, and

In this study, the role of attention in facial expression processing is investigated, especially as it relates to fearful facial expressions compared to happy facial expressions. Facial fear processing plays a critical role in human social interactions and survival, and this has previously been studied mainly in animal models. This study, however, was accomplished with the presentation of images of actors with happy and fearful facial expressions in three spatial frequency formats, as it is hypothesized that images at different spatial frequencies may be processed via different pathways. These images were presented to human participants in two experiments. In Experiment I, facial expression was task-relevant as participants were asked to discriminate between “happy” and “fear” expressions with reaction time (measured in seconds) and accuracy recorded. In Experiment II, facial expression was task-irrelevant, as participants were asked simply to discriminate between photographs of males and females, again with reaction time and accuracy recorded. Overall, the results comparing happy and fearful facial expressions in Experiment I were not significant. The results comparing happy and fearful facial expressions in Experiment II exhibited similar insignificant results except for accuracy in certain spatial frequencies, which were found to be significant. These results suggest that fearful facial expressions are processed more accurately than happy facial expressions when attention is focused on other variables in the image rather than when attention is focused on the facial expressions themselves.
Date Created
2024-05
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Effect of Peer Feedback Presence on Working Memory Performance

Description

Students in academic environments receive near-constant feedback about both their own abilities as well as the performance of their peers which could significantly alter their cognitive and learning outcomes. This research investigates whether this social feedback concerning peer ability would

Students in academic environments receive near-constant feedback about both their own abilities as well as the performance of their peers which could significantly alter their cognitive and learning outcomes. This research investigates whether this social feedback concerning peer ability would improve students’ cognitive performance as measured by a visual working memory (VWM) task. Specifically, the present study provides either positive or negative feedback by means of peers’ performance to test for changes in the quality (memory precision) and the memorability (memory failure rate) of visual working memory representations. The effect of feedback on individual confidence was also examined, as feedback might impact subjective confidence instead of object task performance. Memory precision, participant guess rate, and confidence were compared across both halves of the experiment to determine potential time differences. Participants (N=105) were each administered a 300-trial Delayed Estimation Task to assess visual working memory ability. Participants were asked to rate their confidence in their task response after each trial and were all informed of their own response accuracy after every block of 30 trials. Along with personal feedback after each block, individuals were randomly assigned to view feedback ranking their performance as more or less accurate than other students. Results indicate a nonsignificant effect of peer feedback type on individual memory precision, guess rate, and confidence, which ran contrary to experimental hypotheses. These trends could have occurred due to the presence of participant-based moderating factors that could impact how certain individuals respond to feedback. Additionally, significant increases in both the precision of participants’ memory representations and the rate at which they guessed on the Delayed Estimation Task were observed across time. Together, these findings highlight the need for further research on the nuanced effects of social feedback on neural processing in order to improve student cognition over time.

Date Created
2022-12
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The Impact of Attentional Priority on the Interaction Between Working Memory Representations

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Description

The present study researched the systematic biases in working memory and how items interact with each other in working memory. The first goal of the study was to assess whether working memory representations of one another or systematically interact. This

The present study researched the systematic biases in working memory and how items interact with each other in working memory. The first goal of the study was to assess whether working memory representations of one another or systematically interact. This was tested by the repulsion bias in the representations. The second goal was to test whether the interaction is modulated by attentional priority. Attended items exhibited a weaker repulsion bias indicating that attention helped to protect the representation from the impact of the un-attended item.The average mean error for the unattended item was 3.68º while for the attended item it was 2.19º. These results are consistent with the hypothesis that items in working memory systematically interact with each other and further suggests that the main theories in working memory that do not assume interactions need to be updated.

Date Created
2022-05
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Motivated Memory: Structural and Functional Neural Correlates

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Description
Capacity limits of the human nervous system require important or rewarding information to be prioritized and encoded over less important or rewarding information. The present dissertation aims to identify structural and functional neural correlates of reward-motivated memory encoding. Chapter 1

Capacity limits of the human nervous system require important or rewarding information to be prioritized and encoded over less important or rewarding information. The present dissertation aims to identify structural and functional neural correlates of reward-motivated memory encoding. Chapter 1 reviews studies of reward-motivated memory encoding and their neural correlates, as well as the structure and function of dopaminergic midbrain circuits. Chapter 2 presents a study that utilizes electroencephalography (EEG) to determine which of two hypothesized processes underly the influence of reward value on episodic memory. One hypothesis is that value engages prefrontal executive control processes, so that valuable stimuli engage an elaborative rehearsal strategy that benefits memory. A second hypothesis is that value acts through the reward-related midbrain dopamine system to modulate synaptic plasticity in hippocampal and cortical efferents, thereby benefiting memory encoding. The results revealed that EEG signals thought to index dopamine-driven attention allocation were modulated by reward value and were positively correlated with individual differences in behavioral measures of memory prioritization. Chapter 3 employs diffusion-weighted magnetic resonance imaging (MRI) to dissociate heterogenous functional circuits of the midbrain reward system. The results comport with primate histology and show that midbrain circuits are differentially predictive of impulsivity and of attention-deficit hyperactivity disorder (ADHD). Chapter 4 presents a study that also employs diffusion-weighted MRI. The findings replicate Chapter 3 in dissociating heterogenous functional circuits of the midbrain reward system. Additionally, the structural integrity of midbrain-hippocampus circuits was quantified. Structural integrity of these circuits was positively correlated to behavioral measures of memory prioritization. These findings suggest that structural and functional measures of the dopaminergic reward system may underlie reward-motivated memory encoding in humans.
Date Created
2021
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