When people notice new things in their environment, it tends to help them remember things better afterward. However, new research published in the Journal of Psychopathology and Clinical Science indicates that this “novelty boost” in memory performance is reduced among those with paranoid tendencies.
The new study was motivated by the desire to better understand the relationship between memory impairment and psychotic-like symptoms, particularly focusing on paranoia, in individuals across the psychosis spectrum. Memory impairment is a well-documented feature of psychosis disorders, including schizophrenia, and it is associated with functional impairments. However, the mechanisms underlying this memory dysfunction are not well understood.
Previous research has primarily focused on the associations between memory and the negative and disorganized symptom clusters of schizophrenia. Positive symptoms, such as paranoia and positive schizotypy, have received less attention in terms of their relationship with memory deficits. Recent studies have suggested that individuals with positive symptoms might have difficulty with novelty detection (noticing that new things in their environment are in fact new).
“People often associate memory deficits with neurodegenerative diseases like Alzheimer’s – but memory dysfunction is also a core feature of psychosis spectrum disorders like schizophrenia. A growing body of research points to similar memory deficits among people who exhibit psychotic-like experiences that don’t reach the threshold for a diagnosis of schizophrenia,” said study author William N. Koller, a Ph.D. candidate in clinical psychology at Yale University.
“I am interested in exploring how memory function is related to psychotic-like symptoms across this broader spectrum, with the goal of improving our models of why memory goes awry in these contexts so that we can target this symptom more effectively.”
“In the present study, we were motivated by prior work that suggests that paranoia – a common aspect of psychotic-like thought – is associated with difficulty in detecting novelty (i.e., where people higher in paranoia more frequently mistake new stimuli as having been seen before; see here),” Koller explained.
“Noticing novelty in our immediate surroundings typically serves as a powerful cue to our memory system: it signals that we may be entering an unfamiliar environment and need to be on the lookout so that we can effectively encode our new surroundings. Here, we were curious whether people experiencing higher levels of paranoia may struggle to use novelty in this way. If so, it would suggest that these individuals may be missing opportunities to switch into a more externally oriented mode of processing that helps us stay in-tune with the demands of our ever-changing environments.”
For their study, the researchers recruited 450 people through an online platform called Prolific. These participants answered various questions about their personal experiences, including whether they sometimes felt suspicious or mistrustful of others in the past month (e.g., “I was convinced there was a conspiracy against me”).
Then, the researchers administered a memory test to these participants. In the test, the participants viewed a series of pictures of everyday objects. These pictures could be new (never seen before), old (already seen), or similar (looked a lot like the old ones but with small differences). Participants had to say whether each picture was new, old, or similar by pressing certain keys on their keyboard.
The researchers found that participants’ ability to correctly identify similar items was significantly boosted when those items were preceded by judgments of novelty (indicating that they were new) rather than judgments of familiarity (indicating they had been seen before). In other words, participants generally remembered things better when they had just seen something new. This “memory penumbra effect” supported the idea that detecting newness on one trial improved performance on the following trial.
“We used a memory task that required people to watch for subtle changes between the current image and a highly similar image that had been presented earlier in the experiment,” Koller told PsyPost. “Notably, if novelty does help to switch us into a mode where we are more attentive of the outside world, people should be better at noticing these subtle differences when they are preceded by a new, unfamiliar image (versus an old, familiar image). Sure enough, this is the exact pattern that we saw when we collapsed across all participants.”
Importantly, there was a significant interaction between paranoia and the effect of preceding responses on memory performance. As participants’ paranoia increased, their memory benefits from detecting novelty decreased. In other words, participants with higher paranoia were less impacted by preceding judgments of novelty compared to those with lower paranoia when it came to correctly identifying similar items.
“Some participants received more of a ‘novelty boost’ than others,” Koller told PsyPost. “Namely, people higher in paranoia tended to receive less of a benefit from preceding instances of novelty detection. This contributes to our understanding of how the memory system might function differently in psychosis, suggesting that those experiencing paranoia struggle to use novelty to switch into a more externally oriented mode of processing. These missed opportunities to turn outward and notice changes in the external world may make it difficult to stay in step with one’s environment, thus contributing to perceptions of the world as unpredictable, uncertain, and/or threatening.”
But the study, like all research, includes some limitations. The study was conducted with a non-clinical convenience sample primarily composed of White participants. The results might not apply to more diverse populations. While the study established an association between paranoia and reduced benefit from novelty detection, additional research is needed to understand why this occurs and the cognitive mechanisms involved.
“It is important to note that this study was conducted among online workers (using the Prolific platform) and relied on self-reported experiences of paranoia,” Koller explained. “While this strategy has its benefits, in that it allows for the collection of large samples and can help avoid confounds frequently found in studies conducted in medical contexts (e.g., medication status), it will be informative to replicate this study using an in-person sample and among people with diagnoses of schizophrenia. This will help determine whether this pattern extends to those experiencing more severe symptoms of psychosis.”
“We have learned a lot about schizophrenia in the past decades, but it remains highly stigmatized, and people often hesitate to talk about it,” Koller added. “At the same time, it is more common than one might think, affecting around 1 in 100 people, with many more experiencing subthreshold psychotic-like thoughts or experiences. I hope that this work contributes in some small way to the demystification of psychosis, helping to highlight how certain aspects of this experience in fact extend across a broad spectrum of the population.”
The study, “Reduced Benefit of Novelty Detection on Subsequent Memory Judgments in Paranoia“, was authored by William N. Koller and Tyrone D. Cannon.
