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The ability to accurately recall rich episodic memories and the decision-making strategies used in memory-based tasks are critical in many real-world contexts, such as legal testimony, healthcare, and education. Criterion shifting is a decision-making strategy that adjusts decision thresholds based on individual task demands and has been found to be a uniquely stable cognitive trait. The goal of this research was to systematically explore criterion-shifting behavior in ecologically valid scenarios, focusing on recollection processes and the influence of social external factors. The research begins with an ecologically valid scenario in Experiment 1 (Chapter 2), where criterion manipulations were introduced during an interview to examine how participants adjusted their recall strategies after a stressful autobiographical episodic event. The findings revealed that conservative instructions led to stricter decision criteria and more selective recall, whereas liberal instructions did not significantly lower the already liberal baseline criterion. Given these results, the subsequent experiments aimed to systematically examine how criterion shifting functions in both controlled laboratory settings and more ecologically valid scenarios, providing insights into how individuals adapt their decision-making strategies across different contexts.Experiments 2 and 3 (Chapter 3), in a controlled laboratory setting, isolate the components of social context and criterion shifting. Experiment 2 investigates how competition and public rankings influence criterion shifting during recognition memory tasks, while Experiment 3 considers how collective outcomes influence performance in a group-based task. Neither experiment found significant impacts from social pressure on criterion shifting tendencies, supporting the view that such tendencies are stable cognitive traits. However, Experiment 3 revealed that collective outcomes can enhance discriminability when tasks are relatively easy, suggesting that social influences may improve memory performance under favorable conditions. Experiment 4 (Chapter 4) focused on understanding recollection processes through a within-subject design that systematically increased reliance on recollection across image recognition and word cue tasks. This study tested predictions from the Dual Process Signal Detection (DPSD) model, which views recollection as a thresholded process, and the Unequal Variance Signal Detection (UVSD) model, which treats recollection as a continuous process with Gaussian memory strength distributions. The results revealed consistent criterion shifting across both tasks, indicating that participants employ a generalized decision-making strategy that adapts to varying cognitive demands. The linearity of the z-transformed ROC curves further supports the UVSD model’s predictions, which challenges the DPSD model’s assumption that recollection is a discrete process.Overall, this dissertation contributes to a broader understanding of how criterion shifting operates in diverse contexts, providing insights into the stability of this cognitive trait across different memory tasks and the extent to which social factors and recollection processes influence decision-making. The findings underscore the need for future research to further explore criterion shifting with ecological validity in mind.

Individuals should strategically shift decision criteria when there are disproportionate likelihoods or consequences for falsely identifying versus missing target items. Despite being explicitly aware of the advantages for criterion shifting, people on average do not shift extremely, leading many theories to conclude that people are generally suboptimal at placing decision criteria. However, assessments of individual differences reveal that some people do shift criteria quite well while others fail to shift entirely. These individual differences are remarkably consistent across time, tasks, and decision domains, yet cannot be adequately explained by other cognitive or personality measures—the degree to which people shift a criterion is a stable, uniquely individualistic cognitive trait. Individuals who inadequately shift criteria are capable of shifting to greater extents but appear unwilling to do so. Understanding criterion shifting tendencies at the individual level is vital since assessments of group averages fail to capture the true nature of this behavior. These individual differences carry important implications for investigating the neural mechanisms that underly the placement of a decision criterion.The role of the decision criterion is often neglected in neuroimaging studies. For instance, widespread frontoparietal activity is consistently observed in recognition memory tests that compare studied (“target”) versus unstudied (“nontarget”) responses. However, there are conflicting accounts that ascribe various aspects of frontoparietal activity to mnemonic evidence versus decisional processes. According to Signal Detection Theory, recognition judgments require individuals to decide whether the memory strength of an item exceeds a decision criterion for reporting previously studied items. Yet, most fMRI studies fail to manipulate both memory strength and decision criteria, making it difficult to appropriately identify frontoparietal activity associated with each process. Systematic manipulations of criteria and discriminability revealed that maintaining a conservative versus liberal decision criterion drastically affects frontoparietal activity in target versus nontarget response contrasts, whereas changes in discriminability showed virtually no differences. Findings from dense-sampling fMRI data revealed multiple frontoparietal networks associated with inhibiting prepotent responses whereas the default mode network is relatively more engaged when participants provide a prepotent response. This supports a response bias account of recognition memory indicating that widespread frontoparietal activity observed during recognition memory tests is largely attributable to decisional processes. Attempts to modulate decision criteria using neurostimulation have unfortunately failed to provide a causal link between frontoparietal activity and criterion placement, despite the robust fMRI correlates suggesting that such a relationship should exist.