Pupillary Dilation During Recognition Memory: Episodic Recovery or Goal Attainment?

A robust finding in eye tracking studies of memory is that successful recognition of studied (i.e., old) items yields greater pupillary dilation compared to the successful recognition of unstudied (i.e., new) items. This is termed the “pupil old/new effect” based on the reasonable assumption that the fundamental difference between recognizing old and new items is the presence of episodic content for old material, and thus the pupil dilation response reflects the increased cognitive load incurred when episodic content is successfully retrieved (Goldinger & Papesh, 2012; Beatty, 1982; Kahneman, 1973). While that may be the case, it is also possible that subjects are internally motivated to detect studied materials more so than unstudied materials. Thus, the cognitive basis of the pupil old/new response remains unclear because typical memory paradigms do not control for the motivational significance of recognition memory decisions.

I am using a performance-based incentive paradigm to manipulate motivation during recognition memory, incentivizing only “old” or only “new” judgments for each test block. Thus, I am testing the hypothesis that pupillary dilation during recognition memory reflects goal attainment and not the recovery of episodic content.

 

 

The Effects of tDCS on Decision Bias and Pupillary Dilation During Recognition Memory

Recognition memory–the ability to distinguish novel from familiar stimuli–depends not just on our past experience (or lack thereof) with a stimulus, but also on our expectations given the environmental context in which it is encountered. Indeed, our expectations are known to influence our willingness to claim that something has been previously experience (i.e., response bias). Even so, virtually nothing is known about the cognitive and neural mechanisms that underlie adaptive, ‘on-the-fly’ changes in recognition bias. I will use an explicit cueing paradigm, which directly manipulates participants' expectations, in combination with non-invasive brain stimulation to test whether left lateral posterior parietal cortex (PPC) has a functional role in biasing recognition memory decisions and whether any changes in bias are reflected in pupillary dilation (an implicit measure of recognition). 

 

 

False Positive Feedback and Criterion Shifts in Recognition Memory

The purpose of this project is to use tDCS to determine whether posterior parietal cortex (PPC) has a functional role in incorporating expectations into recognition memory decisions. In other words, whether PPC is involved in adaptively biasing whether stimuli are judged “old” or “new”. I will use Dr. Dobbins’ explicit cueing memory paradigm that manipulates recognition bias, in combination with tDCS and pupillometry, to test the hypothesis that stimulation of left lateral PPC will produce greater changes in response bias and pupillary dilation for cued items compared to uncued items.

 

 

Sequential Dependencies in Metacognitive Confidence

Correlations between adjacent responses—known as sequential dependencies—in detection tasks have been well known to perception researchers for decades (e.g., Howarth, & Bulmer; 1956). However, sequential dependencies in metacognitive confidence ratings assessed during recognition memory have never–to the best of our knowledge–been reported in the literature. Thus, Dr. Dobbins (along with Dr. Kantner, now at UC Northridge) began investigating whether sequential dependencies exist in recognition confidence judgments. Upon my arrival to the lab I joined this ongoing project. Dr. Dobbins and Dr. Kantner (manuscript in prep.) had previously found that (1) sequential dependencies exist in recognition confidence judgments, (2) these sequential dependencies persist when a perceptual task (gender identification) was interleaved between recognition trials, and (3) these sequential dependencies persist whether the intervening task was easy or difficult (not blurred faces or blurred faces, respectively), but even more so when the perceptual task was difficult. I have been working on several follow-up studies. Specifically, I tested whether manipulating the difficulty of the perceptual task within subjects would moderate or amplify the effects of difficulty previously found between subjects. Secondly, we added confidence ratings to the gender identification task to test whether the effect of one confidence rating on another is domain specific or domain general.

 

 

Metacognition and Eye Movement Indices of Associative Recognition Memory

JOLs during encoding predict eye movements during recognition.

The purpose of this project is to use tDCS to determine whether posterior parietal cortex (PPC) has a functional role in incorporating expectations into recognition memory decisions. In other words, whether PPC is involved in adaptively biasing whether stimuli are judged “old” or “new”. I will use Dr. Dobbins’ explicit cueing memory paradigm that manipulates recognition bias, in combination with tDCS and pupillometry, to test the hypothesis that stimulation of left lateral PPC will produce greater changes in response bias and pupillary dilation for cued items compared to uncued items.

 

 

Lisa A. Solinger