Schizotypy and false memory

Aberrant memory and delusional ideation: A pernicious partnership?

Delusions can be conceptualized as beliefs that are both at odds with consensus reality and espoused with high conviction. While delusions represent a cardinal symptom of schizophrenia, delusion-like beliefs can be found in the general population. Do similar cognitive mechanisms support delusionality across this spectrum? If so, what are they? Here, we examine evidence for a mechanistic role of the (associative) memory system in the formation and maintenance of delusions and delusion-like beliefs. While general neurocognitive metrics do not tend to associate with delusionality, our scoping review of the clinical and subclinical literature reveals several subdomains of memory function that do. These include a propensity to commit errors of commission (i.e., false alarms and intrusions), source memory biases, and metamemory impairment. We discuss how several of these effects may stem from aberrant associative memory function and offer recommendations for future research. Further, we propose a state/trait interaction model in which underlying traits (i.e., impaired associative and metamemory function) may become coupled with delusionality during states of acute psychosis, when memory function is particularly challenged by aberrant salience attribution and noisy perceptual input. According to this model, delusions may arise as explanations to high-salience (but low-source) mnemonic content that is endorsed with high confidence.

Thinking style and psychosis proneness do not predict false insights

The FIAT paradigm (Grimmer et al., 2021) is a novel method of eliciting 'Aha' moments for incorrect solutions to anagrams in the laboratory, i.e. false insights. There exist many documented reports of psychotic symptoms accompanying strong feelings of 'Aha!' (Feyaerts, Henriksen, Vanheule, Myin-Germeys, & Sass, 2021; Mishara, 2010; Tulver, Kaup, Laukkonen, & Aru, 2021), suggesting that the newly developed FIAT could reveal whether people who have more false insights are more prone to psychosis and delusional belief. To test this possibility, we recruited 200 participants to take an adapted version of the FIAT and complete measures of thinking style and psychosis proneness. We found no association between experimentally induced false insights and measures of Schizotypy, Need for Cognition, Jumping to Conclusions, Aberrant Salience, Faith in Intuition, or the Cognitive Reflection Task. We conclude that experiencing false insights might not be constrained to any particular type of person, but rather, may arise for anyone under the right circumstances.

A population-based cross-sectional study of cognitive deficits in paranoia

This study sought to investigate the association between paranoia and performance in a range of neurocognitive domains using a large community sample. We conducted a cross-sectional survey of 4507 individuals within the PISMA-ep Study. We used a large community sample selected after multistage sampling using standard stratification techniques. Socio-demographic variables such as age, gender, educational level, urbanicity, and geographical region were recorded. The Spanish version of the Green Paranoid Thought Scale (S-GPTS) was used to assess paranoid thoughts. The Screening for Cognitive Impairment in Psychiatry (SCIP) was used to assess neurocognitive performance both globally and by domains (i.e., immediate and delayed verbal learning, working memory, verbal fluency and processing speed). Individuals with high S-GPTS paranoia scores showed significantly lower performance on global cognitive function and also on immediate (but not delayed) verbal learning, working memory, verbal fluency and processing speed. These results held statistical significance even after controlling for the effects of education and estimated IQ. We propose that cognitive deficits may be mediators of paranoid thinking formation and need to be considered when assessing patients with high levels of paranoia.

Positive Schizotypy Increases the Acceptance of Unpresented Materials in False Memory Tasks in Non-clinical Individuals

Enhanced spreading of semantic activation has been hypothesized to underlie some of the most significant symptoms of schizotypal personality, like thought disorder, odd speech, delusion, or magical thinking. We applied the Deese/Roediger-McDermott false memory task to the study of semantic activation in a group of 123 non-clinical individuals varying in the three dimensions of schizotypal personality: positive, negative and disorganized schizotypy. In the study phase, we presented them with lists composed of words semantically associated to unpresented critical words. Then, they responded to a recognition questionnaire including previously presented words and critical unpresented lures, as well as weakly related and unrelated unpresented lures. Participants rated their confidence in recognizing each word. They also filled in a standardized schizotypal personality questionnaire. Confirming the false memory effect, recognition ratings provided in response to critical words were higher than those produced for both weakly related and unrelated items. Crucially, scores in the positive dimension increased recognition percentages and confidence ratings for weakly related and unrelated lures. This study indicates that high levels of positive schizotypy might influence the tendency to accept false memories of unrelated unpresented material.

High delusional ideation is associated with false pictorial memory

BACKGROUND AND OBJECTIVES

To assess the relationship between false memories and schizotypal experiences in healthy volunteers. Previous research has examined a number of schizotypal dimensions and experiences and found a variety of results. Our aim was to determine the specificity of these associations by giving participants a schizotypy measure which tapped positive, negative and disorganised dimensions (O-LIFE) and another which focused on delusional ideation (PDI).

METHODS

A new memory task was used consisting of images of everyday items, separated into categories. At test participants were presented with pictures which had been seen in the study phase, related lures (additional items from the same categories but which were new) and new items which were not from these categories.

RESULTS

Positive correlations were found between scores on the positive dimension of schizotypy/delusional ideation and proportion of false memories. Moreover, these participants also had a greater tendency to respond with the highest confidence old response, regardless of the status of the item. No significant correlations were found with the other dimensions of schizotypy.

LIMITATIONS

The confidence finding differs somewhat from previous research, which has found more confidence in memory errors and less confidence in correct responses in schizophrenia. It is unclear the reason(s) for this discrepancy.

CONCLUSIONS

Increased false memory is associated with the positive dimension of schizotypy and delusional ideation and not the disorganised or negative dimensions. Furthermore, our results suggest that those high in positive schizotypy/delusional ideation require less evidence before they are willing to call an item old.

High and low schizotypal female subjects do not differ in spatial memory abilities in a virtual reality task

INTRODUCTION

Schizotypy is a psychological construct related to schizophrenia. The exact relationship between both entities is not clear. In recent years, schizophrenia has been associated with hippocampal abnormalities and spatial memory problems. The aim of this study was to determine possible links between high schizotypy (HS) and low schizotypy (LS) and spatial abilities, using virtual reality tasks. We hypothesised that the HS group would exhibit a lower performance in spatial memory tasks than the LS group.

METHODS

Two groups of female students were formed according to their score on the ESQUIZO-Q-A questionnaire. HS and LS subjects were tested on two different tasks: the Boxes Room task, a spatial memory task sensitive to hippocampal alterations and a spatial recognition task.

RESULTS

Data showed that both groups mastered both tasks. Groups differed in personality features but not in spatial performance. These results provide valuable information about the schizotypy-schizophrenia connections.

CONCLUSION

Schizotypal subjects are not impaired on spatial cognition and, accordingly, the schizotypy-schizophrenia relationship is not straightforward.

Altered time-perception performance in individuals with high schizotypy levels

The possibility of altered time-perception in high schizotypy scorers, as postulated through previous differences shown in performance between high and low scorers in schizotypy on schedules of reinforcement with temporal elements, was examined using a series of retrospective timing tasks. Three stimuli ratio manipulations were made across two experiments, and, using an adjusted version of the bisection-point method for data analysis, results showed that high scorers on the Unusual Experiences subscale of the O-LIFE(B) estimated the mid point of the stimulus range to be at a significantly longer interval than low scorers. This was true when the ratios between "short" and "long" standard stimuli were 4:1 (Experiment 1), 3:1 and 2:1 (Experiment 2). These findings are consistent with the notion of altered time-perception for high schizotypals.

The relationship between schizotypal ideation and subjective cognition reflects more than just cognitive disorganisation: introducing the Brief Cognitive Schizotypy Index

INTRODUCTION

Internet surveys of psychometric schizotypy can usefully explore the relationship between the schizophrenia spectrum and cognition, but significant participant drop-out can be a difficulty. We aimed to identify the aspects of schizotypal thinking associated with self-reported cognitive difficulties with a view to developing a brief index of schizotypy that is maximally sensitive to subjective cognitive complaints.

METHOD

Two online surveys were launched over two years. One explored schizotypal personality and subjective cognition. The other provided data for principal components analyses. The OLIFE was used in both surveys alongside other more specific measures of schizotypal features and a measure of affect.

RESULTS

Fifteen OLIFE cognitive disorganisation items, seven OLIFE unusual experiences items and three OLIFE introvertive anhedonia items were reliably associated with a range of self-reported cognitive difficulties as measured by the Cognitive Failures Questionnaire. The 25 items of the new Brief Cognitive Schizotypy Index (BCSI) loaded on three factors, labelled Unusual experiences, Affect and Cognition. The BCSI correlated strongly with a propensity to hallucinations scale, a persecutory ideation scale and two other measures of everyday cognition. These correlations survived correction for the role of prevailing negative affect.

CONCLUSIONS

Particular aspects of schizotypal ideation, reflecting the full range of such experiences, are related to reports of day-to-day cognitive difficulties. Future work should replicate these findings in a wider sample and explore relationships with objective cognitive measures.

Neuropsychological differentiation of adaptive creativity and schizotypal cognition

Both creativity and schizophrenia-spectrum disorders have been associated with activation of remote semantic concepts, but this activation results in innovative output in one case and communication disturbances in the other. The present study examined the relationship between monitoring semantic information (which relies on executive brain function), creativity, and characteristics of schizotypy in an undergraduate population. Results indicate that executive function differentiates the use of semantic information in creativity and schizotypy. Specification of the balance between executive monitoring and activation of semantic information is important for determining how communication disturbances manifest, and for the measurement of creativity and schizotypy in the general population.

Schizotypal trait in healthy women is associated with a shift away from dextrality on a spatial motor control task, but not on a force control task

It is generally acknowledged that schizophrenia and schizotypy lie on the same continuum, while there is an ongoing debate as to whether schizotypy represents true dimension or quasi-dimension. Evidence suggests that reduced hemispheric lateralization and mixed handedness are associated with both schizophrenia and schizotypy. However, the possible relationship of schizotypy with laterality as assessed with motor function tasks has not been well documented. A few studies using fine motor control tasks have demonstrated the relationship between schizotypy and reduced laterality among student populations, yet little has been done in community samples. Here we employed 249 healthy women and examined the association between schizotypal traits assessed with the Schizotypal Personality Questionnaire and motor functions assessed with the Purdue Pegboard test (as a measure of spatial motor control) and a handgrip force test. Correlational and categorical analyses both showed that schizotypal traits were significantly associated with leftward and bilateral bias in the fine motor control task, but not in the handgrip force test. Schizotypy did not significantly affect the performance level on either of these tasks. These results indicate that schizotypal traits in healthy women are associated with a shift away from dextrality, supporting the fully dimensional model of schizotypy.

Recall of false memories in individuals scoring high in schizotypy: memory distortions are scale specific

BACKGROUND AND OBJECTIVES

Previous research has indicated abnormal semantic activation in individuals scoring higher in schizotypy. In the current experiment, semantic activation was examined by using the Deese-Roediger-McDermott paradigm of false memories.

METHODS

Participants were assessed for schizotypy using the Oxford-Liverpool Inventory of Feelings (OLIFE). Participants studied lists of semantically related words in which a critical and highly associated word was absent. Participants then recalled the list.

RESULTS

Participants high in Unusual Experiences and Cognitive Disorganization recalled more critical non-presented words, weakly related studied words, and fewer studied words than participants who scored low on these measures.

LIMITATIONS

Previous research using the cognitive-perceptual factor of the Schizotypy Personality Questionnaire found reduced false memories, while the Unusual Experiences subscale of the OLIFE was associated with more false memories. Both scales cover similar unusual perceptual experiences and it is unclear why they led to divergent results.

CONCLUSIONS

The findings suggest that subtypes of schizotypy are associated with abnormal semantic activation.

False memory in schizophrenia patients with and without delusions

Delusions are fixed 'false beliefs' and, although a hallmark feature of schizophrenia, no previous study has examined if delusions might be related to 'false memories'. We used the classic Deese-Roediger-McDermott (DRM) paradigm to compare false memory production in schizophrenia patients who were currently experiencing delusions (ED), patients not experiencing delusions (ND) and healthy control participants. The ED group recalled twice as many false-positive memories (i.e., memory for words not previously seen) as both the controls and crucially, the ND group. Both patient groups also recognised fewer correct words than the healthy controls and both showed greater confidence in their false memories; however, on the recognition task, the ED group made more false-negative (i.e. rejecting previously seen words) high confidence responses than the ND group.

Effects of positive and negative delusional ideation on memory

We investigated the relationship between levels of delusional ideation (whether positive or negative delusions) and the activation and distortion of memory by using pairs of positive and negative adjectives describing personality traits where those adjectives had similar meanings. We presented one of each pair of adjectives in the learning phase. Immediately after the learning phase in Experiment 1, we asked whether each adjective had been presented. Participants with high (positive or negative) delusional ideation were more likely to indicate that they had learned adjectives that they had not actually learned. This finding suggested that non-learned positive (or negative) adjectives that were associated with learned negative (or positive) adjectives were more likely to be activated in participants prone to positive (or negative) delusional ideation. However, in Experiment 2, two forced-choice tests were conducted immediately after the learning phase. In this context, participants, regardless of their proneness to delusional ideation, could almost always correctly distinguish what had and had not been presented, suggesting that the activation of learned items was still stronger than that for non-learned items in the immediate test. As time passed, the proportion of false alarms for positive or negative adjectives was higher in the two forced-choice tests among those with high proneness to (positive or negative) delusional ideation, suggesting that participants with delusional ideation were increasingly likely to depend on internal conditions for retrieval over time. Nous avons examiné la relation entre les niveaux d'idéation illusoire (qu'elle soit positive ou négative) et l'activation et la distorsion de la mémoire, en utilisant des paires d'adjectifs positifs et négatifs à significations similaires décrivant des traits de personnalité. Nous avons présenté un membre de chaque paire d'adjectifs lors d'une phase d'apprentissage. Dans une première expérience, immédiatement après la phase d'apprentissage, nous avons demandé si chaque adjectif avait été présenté. Les participants ayant un niveau d'idéation illusoire (positive ou négative) élevé étaient plus susceptibles d'indiquer qu'ils avaient appris les adjectifs qu'ils n'avaient pas appris. Ce résultat suggérait que les adjectifs positifs (ou négatifs) non appris qui étaient associés à des adjectifs négatifs (ou positifs) appris étaient plus susceptibles d'être activés chez les participants portés à l'idéation illusoire positive (ou négative). Dans une deuxième expérience, deux tests à choix forcés ont été menés immédiatement après la phase d'apprentissage. Dans ce contexte, les participants, indépendamment de leur tendance à l'idéation illusoire, pouvaient presque toujours distinguer correctement ce qui avait été présenté de ce qui n'avait pas été présenté, suggérant que l'activation des items appris était encore plus forte que celle des items non appris dans le test immédiat. Avec le temps, la proportion de fausses alarmes pour les adjectifs positifs ou négatifs était plus élevée dans les deux tests à choix forcés chez les participants portés à l'idéation illusoire (positive ou négative), ce qui suggère que les participants avec idéation illusoire étaient de plus en plus susceptibles de dépendre de leurs conditions internes lors du rappel à mesure que le temps passait. En este estudio se investigó la relación entre los niveles de ideación delusional (tanto delusiones positivas como negativas) y la activación y distorsión de la memoria a través del uso de pares de adjetivos positivos y negativos que describen rasgos de personalidad. Estos pares de adjetivos tenían significados similares. En la fase de aprendizaje se presentó un miembro de cada par de adjetivos. Inmediatamente después de la fase de aprendizaje se realizó el primer experimento, en el cual se preguntó al participanten si es que se le habían presentado cada uno de los adjetivos. Los participantes con elevada ideación delusiva (positiva o negativa) reportaran con una mayor probabilidad haber aprendido adjetivos que en realidad no se les había presentado. Este hallazgo sugiere que adjetivos positivos (o negativos) no aprendidos que estaban asociados con adjetivos negativos (o positivos) aprendidos, tenían una mayor probabilidad de ser activados en participantes propensos a una ideación delusiva positiva (o negativa). En el segundo experimento se llevaron a cabo inmediatamente después de la fase de aprendizaje dos pruebas de decisión forzada. En este contexto se pudo observar que los participantes a pesar de su tendencia hacia una ideación delusional, lograron distinguir en la mayoría de los casos correctamente entre los adjetivos que les fueron presentado y lo que no. Esto sugiere que la activación de los items aprendidos fue mucho más intensa que la de los items no aprendidos en el test. Sin embargo se pudo observar en los participantes de las dos pruebas de decisión forzada que con el paso del tiempo el porcentaje de falso reconocimiento de adjetivos positivos y negativos fue más elevado entre aquellas personas con una alta tendencia hacia una ideación delusional (positiva o negativa). Esto sugiere que en participantes con ideación delusional el reconocimiento de información a lo largo del tiempo probablemente es muy dependiente de condiciones internas.