Computational dissection of schizotypy: differential contingency weighting

Schizotypy is a personality dimension related to psychotic experience, i.e., alteration of beliefs and sensory experiences, also is a liability for schizophrenia. In this dissertation I focus on schizotypy and its relationship with perceptual, learning, and agency. I employed computational models, and Contingency Learning Theory as a general framework, to develop novel behavioural tasks used to dissect cognitive features of schizotypy measured in the general population. I studied the Jumping-to-Conclusions bias with a novel perceptual contingency task (Experiment 1). This task also tests the tendency to perceive associations between events. I found that people scoring high on schizotypy does not perceive associations easily, but they gather more sensory evidence to make correct decisions. In addition, I investigated whether schizotypy moderates how people use absent information to make judgments (Experiments 2 and 3). In an exploratory analysis, I found that high unusual experiences scores were negatively correlated with how people use the absence of events to judge event relatedness. Moreover, I developed a framework −behavioural paradigm and computational model− to study how two agents (one human and one artificial) interact and make judgments of control (Experiments 4 and 5). I used this task to study illusion of control and how people weight external and internal events as sources of control. I found that people scoring high in positive schizotypy have an enhanced illusion of control when estimating their control. Although, this result is dependent on participants not ‘interacting’ with another agent. I also found that unusual experiences in schizotypy negatively correlate with sensitivity to external controllers (or agents). In summary, I found that weighting sensory evidence varies in relation to schizotypy. This was supported with my results showing a bias to gather more evidence, a weight reduction for absent information, an enhanced illusion of control when there is nothing else competing for the control, and a reduced sensitivity to perceived control from another agent. Together, my results indicate that high positive schizotypy is related to downweighting sensory evidence with a low saliency baseline (absence of target information, and other agents). Finally, I explored the differences in the concept of weight in computational modelling and I conclude that mathematically different models refer to a similar mechanism, a value multiplying a discrepancy learning signal

The wolf or the sheep? Paranoid and teleological thinking give rise to distinct social hallucinations in vision

Paranoia (belief that others intend harm) and excessive teleological thinking (ascription of purpose to events) are problematic because they can cause a departure from consensual reality. Aberrant theorizing about other minds has been implicated in these higher-level cognitive processes. But we know that human vision can also detect social agents and extract rich information about their goals and intentions even before higher-level theory-of-mind processes are engaged. Might paranoia and teleological thinking have roots in earlier visual perception? Using simple displays that evoke the impression that one disc (the ‘wolf’) is pursuing another (the ‘sheep’) amongst distractors, we find that human participants with more paranoid and excessive teleological thinking tend to perceive chasing even when there is none (experiments 1 and 2) — errors that might be characterized as “social hallucinations”. However, in both between- (experiment 3) and within-participant designs (experiments 4a and 4b), we find that paranoid people have problems detecting sheep, while those high in teleology have problems detecting wolves — each confidently mis-ascribing that role (the wolf for teleology, the sheep for paranoia) to the wrong discs. Moreover, both types of errors correlate with hallucinatory percepts in the real world. These data demonstrate that different people are prone to hallucinate different kinds of social relationships — each colored by different beliefs about intentions, each with their own phenomenology and cognitive/emotional consequences, yet each operating even in visual detection itself, beyond higher-level reasoning

Delusional unreality and predictive processing

In their recent correspondence Feyearts and colleagues highlighted some similarities and differences between their phenomenological approach to delusions and the predictive processing explanation. In the present work we home in on some key points in the exchange and present data that show predictive processing can indeed explain the pervasive sense of unreality that characterizes some delusions (but by no means all of them). Indeed, our data show that some people with delusions and schizophrenia do not report a sense of unreality, and, furthermore, that some people with extreme esoteric beliefs (but no psychotic illness) also report a pervasive sense of unreality. Notably, no healthy control endorsed a sense of unreality (despite endorsing other delusion-like beliefs). By leveraging computational psychiatry, applied to behavioral data gathered during causal learning, we show that unreality experiences in clinical delusions and non-clinical delusion-like beliefs are associated with different types of aberrant prediction errors, prediction error weightings, and learning rates. Taken together, these data suggest that claims of distinction between predictive processing and phenomenological accounts, and that predictive processing cannot explain the sense of unreality, may have been premature. Furthermore, sense of unreality is not pathognomonic of delusion. Finally, these data suggest again that different patterns of prediction error dysfunction are associated with delusions and delusion-like beliefs with different contents, extending recent work to a belief unexamined through predictive processing: delusional unreality

Comparados con horarios estrictos, los horarios flexibles no son inferiores en desenlaces de pacientes ni de residentes

In 2003 in the United States, the accreditation council for graduate medical education (ACGME), conducted national regulatory changes in the established schedules for training residents, this in order to prevent medical errors associated with fatigue; such intervention was criticized for having low quality evidence. QUESTION: Is there a difference between strict duty hours and flexible duty hours in the training of general surgery residents?En el 2003 en Estados Unidos de América, el consejo de acreditación para la educación médica para graduados (ACGME), realizó cambios nacionales a la regulación de los horarios establecidos para el entrenamiento de médicos residentes, esto con el objetivo de prevenir errores médicos asociadas a la fatiga laboral; dicha intervención fue criticada por contar con evidencia de baja calidad. PREGUNTA: En el entrenamiento de residentes de cirugía general ¿existe diferencia entre un horario estricto vs un horario flexible

Comprehensive rehabilitation and job reintegration of people with severe mental illness in a Latin American country: REINTEGRA study protocol

Abstract Background Despite the increasing use of comprehensive rehabilitation models for people with severe mental illness (SMI), there are still limitations to their implementation and replicability in a consensual way, particularly in Latin American countries. The REINTEGRA program aims to be a standardized model of comprehensive rehabilitation focused on psychosocial and cognitive improvement through a set of interventions on different areas of people’s functionality, with the goal of reintegrating people with SMI into the labour market. In this paper we summarize the protocol for its subsequent implementation in a mental health institution in Mexico. Method The protocol is based on a quasi-experimental, prospective longitudinal study, with a pragmatic or naturalistic control group. It will be carried out in three phases. Phase 1 consists of a series of interventions focused on psychosocial improvement; Phase 2 focuses on cognitive and behavioral improvement treatments; and Phase 3 targets psychosocial recovery through rehabilitation and reintegration into the labour market. The overall procedure will be monitored with standarized evaluations at different stages of the program. Discussion This study presents a model of integral rehabilitation of people with SMI. At the moment, one of the obstacles to overcome is the organization and procedural control of the different actors needed for its implementation (nurses, psychologists, doctors, companies, institutions, etc.). REINTEGRA will be the first comprehensive rehabilitation model that includes systematized procedures for job reinsertion for people with SMI in Mexico, which aims to be a standardized tool of easy adaptation and the replicability for other mental health centers and institutions