Abstract. Biographical Sketch

Transcription

1 Abstract In order to function successfully, it is imperative to distinguish between external reality and internally-generated imagery. When visualizing something, we must know whether it is actually out there in the world, or internally created by processes like imagination and memory. We call this ability Perceptual Reality Monitoring (PRM). The failure of Perceptual Reality Monitoring is a hallmark of psychosis. We aim to explore the relationship between PRM, confidence, and general proneness to delusion. We intend do so using a combination of questionnaires and psychophysical tasks administered online to a non-clinical population. Biographical Sketch I was raised in New Milford, CT by my mother, a psychiatric social worker, and my father, an automotive scientist. In many ways, I m exactly what you d expect from a child of my parents. I have their love of the outdoors, their mannerisms, their food preferences. I read books by Jane Goodall, like my mother, and watch Star Trek, like my father. My academic interests fit the pattern. Like my mother, I find the human mind to be the most fascinating, most complex, most important phenomenon I could possibly study. And like my father, I want to be analytical and scientifically rigorous in my approach to problems. It started early. When I was three years old, I asked my uncle, a doctor, for a model brain. He gave me one for Christmas. It was this grey, plastic mass, lumpy, and a little unimpressive given that it represents the thing that is me, you, and most every living creature. I lost interest in the toy pretty quickly, but the curiosity that inspired the request would reappear. At thirteen, I went to a sleep-away summer camp at Skidmore College where I took a three-week summer course. Scrolling through the course offerings, the first line of the description caught my attention: Can animals and machines have minds? I chose that course. It was Philosophy of Mind. Although this progression of interests seems linear, in reality, I didn t know what I wanted to do. I thought I wanted to be a phantasy writer, like Tolkien, or an environmental engineer, or a lawyer, like I always played in mock trials. I got a scholarship to a local private school, took the classes prescribed to me, enjoyed them moderately, and applied to colleges as undeclared. I had been told that college was the time to find one s interests -- usually by declaring a major! But nothing seemed to fit. The biology major didn t have enough math in it, and too much biology. The math major was too abstract. The psychology courses I took were too fluffy. Now statistics and computer science they were great! But I still wanted to study the mind and brain, and that interest wouldn t stop nagging me.

2 Ultimately, I found the College Scholar Program. I designed a course of study I called Computational Neuroscience full of courses that would help me make computer models of the brain. Now, I ve realized it isn t so much the brain that I want to model, but its cognitive functions. And if I could pick a cognitive function, it would be consciousness. Yes, I m using that dirty, fuzzy word. By it, I mean perceptual phenomenology, e.g. what it s like to see the color red. That brings me to where I am now, applying for a summer research grant to study Perceptual Reality Monitoring with the Consciousness and Metacognition lab at UCLA.

3 Marlene Berke, Class of 2019 College Scholar Perceptual Reality Monitoring

4 Statement of Purpose Significance How we distinguish between external reality and internally-generated imagery is an open question, and an important one. When this ability, which we call Perceptual Reality Monitoring (PRM), goes awry, it results in hallucination at best and psychosis at worst. Understanding the relationship between PRM, confidence, and delusion would be a massive step forward in understanding how our reality is created, when it can be trusted, what it is like (of philosophical importance) and what goes wrong in psychosis (of clinical importance). Relation to Existing Research Reality Monitoring is the ability to discriminate between internally and externally generated information (Johnson and Raye, 1981), typically tested using source memory paradigms involving the recollection of whether or not information was generated by participants themselves (Garrison et al. 2017). It much more common to test reality monitoring with memory tasks than perceptual tasks, which is why we re using the term Perceptual Reality Monitoring. However, a recent study used perceptual tasks to test reality monitoring, by inducing auditory hallucinations in healthy volunteers, non-clinical volunteers prone to auditory hallucinations, and clinical populations (Powers et al., 2017). They found evidence that heavily weighting perceptual priors (what one has already seen/experienced) explain the hallucinations. If priors are too strong, you see or hear what you expect. If that is the case, as this previous study suggests, we might expect that those prone to delusional beliefs might form strong priors based on the direction of coherent motion during stimulus presentation, and might tend to hallucinate coherent motion during the delay when there is none. Our proposed work fits into this growing body of studies on Reality Monitoring, with an emphasis on vision and perceptual reality monitoring. Reasons/Plan I m so excited about this research because it gets at how we keep memory and in-themoment reality separate. This is a really interesting cognitive function falling under the umbrella topic consciousness, which is what I m all about. I have some ideas about the results we might see how confidence, PRM performance, and proneness to delusion will correlate statistically but I really don t know what the outcome will be and that s what makes it worth doing. The correlations will help arbitrate between different theories of how PRM works, so we ll hopefully gain insight into this intriguing aspect of consciousness. On the practical side, I m hoping that I can spin this into my honors thesis for my College Scholars major. Being at UCLA will also be a great opportunity for me to visit labs I might want to join for grad school (including Professor Lau s) and to check out other nearby universities.

5 The research will take place at the Consciousness and Metacognition lab at UCLA, under the guidance of Professor Hakwan Lau. His NIH grant will provide compensation for participants in the study. That NIH grant is the only resource that this project will use (aside from the obvious lab computers, stationary, etc). Nitty-Gritty Description of Project We will use Amazon Mechanical Turk, a web-based marketplace where participants complete online tasks in exchange for monetary compensation. First, the participant completes a questionnaire that measures proneness to delusion. This questionnaire, the 21-item Peters et. al. Delusions Inventory (PDI), has been used and validated over the past eighteen years. It asks the participant questions like Do you ever feel as if people are reading your mind? which they answer with a yes or no. If yes, they also indicate on a scale from 1-5 how distressing, preoccupying, and true they find the idea to be. It has been shown (Peters et al., 2004) that, more than the total number of yes answers, ratings of high distress, preoccupation, and truth separate deluded from healthy. We intend to look for any correlation between delusional thinking (as assessed by the PDI questionnaire) with performance (or lack thereof) on the PRM tasks. The experiment runs as follows: the participant is shown a collection of dots moving in the same direction (coherent motion), and they are asked to remember the direction in which the dots are moving. Then, there is a delay, during which dots move randomly. During the delay, the participants must hold the direction of coherent motion in their working memory (WM). That is the internal content. About two-thirds of the time, another pattern of moving dots is briefly flashed (target) during the delay. The target is so brief that it is near the participant s detection threshold: in other words, it s hard for the participant to be sure s/he saw it. One-third of the time, the direction of motion of dots in the target is matched to that of the WM content. The rest of the time, the direction of motion of dots in the target is unmatched to that of the WM content. The participant is then shown two patterns of moving dots, pattern A and pattern B. One matches the content of WM. The participant is prompted to select the pattern that best matches what they saw before the delay. After deciding, they are asked to rate their confidence on a scale from Finally, they are asked whether there was coherent motion during the delay. This task repeats times, with different directions of motion each time. Figure 1 may help visualize the experiment.

6 Figure 1: First, dots with a coherent pattern of motion are displayed. Next comes the delay period, where randomly moving dots are shown. During 66% of trials, the target is flashed. On an unmatched trial (shown here), the direction of coherent motion during the target does not match that held in WM. The participant is then asked to choose, between two patterns of motion, the one that best matches what they have in WM. Not depicted are the confidence rating and the question about coherent motion during the delay. We consider the image held in working memory to be internal content, while the flashed target is perceptual reality. The questions are as follows: how do working memory contents affect detection of the target, how does motion during the delay (target) affect the contents memory, and does performance on this task predict delusional tendencies? Someone with a perfect PRM system, or ability to keep the contents of WM separate from their perceptual reality, would exhibit no affect of match or unmatched WM and target content on ability to detect the target. To the ideal PRM system, working memory content has no bearing on perceptual reality. We might predict that, for most people (those without perfect PRM systems), when the working memory contents and target are matched, it might be easier to choose the correct direction of motion for WM contents, increase confidence in that choice, and increase chance of detecting the target. Conversely, when the WM contents and target are mismatched, we might observe more incorrect answers, reduced confidence, and decreased detection of the target. Might this difference be more exacerbated in participants who score higher on PDI? Perhaps they might confuse the WM and target more often than participants with lower scores, owing to a poorly-functioning PRM system. If so, this could

7 indicate that the same system involved in PRM also generates confidence. Alternatively, participants who score higher on PDI might just think they see something more often, leading to higher confidence ratings and more positive responses when questioned about coherent motion during the delay. Essentially, we want to know how confidence, PRM (as measured by the impenetrability of perceptual reality to WM), and delusional tendencies correlate.

8 Bibliography: Powers A R, Mathys C, Corlett P R. (2017) Pavlovian conditioning induce hallucinations result from overweight of perceptual priors. Science Vol. 357, Issue 6351, pp Simons J S, Garrioson J R, Johnson M K. (2017) Brain Mechanisms of Reality Monitoring. Trends in Cognitive Sciences Vol. 21, Issue 6, pp Garrison J R, Fernandez-Egea E, Zaman R, Agius M, Simons J S. (2017) Reality monitoring impairment in schizophrenia reflects specific prefrontal cortex dysfunction Peters E, Joseph S, Day S, Garety P (2004) Measuring delusional ideation: The 21-item Peters et al. Delusions Inventory (PDI). Schizophr Bull 30: