Schizophrenics know more than they can tell: 
probabilistic classification learning in schizophrenia

Kéri, Szabolcs; Kelemen, Ogúz; Szekeres, György; Bagóczky, Nóra; Erdélyi, Rita; Antal, Andrea; Benedek, György; Janka, Zoltán

doi:10.1017/s0033291799001403

Cited by 74 publications

(59 citation statements)

References 35 publications

(52 reference statements)

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“…This result is consistent with the finding of several studies (Keri et al 2000;Weickert et al 2002;Beninger et al 2003;Keri et al 2005) indicating that the gradual acquisition of probabilistic contingencies in schizophrenia patients may be relatively intact, as well as the idea that different neural systems may support rapid and gradual feedback integration. The gradual integration of probabilistic feedback over many trials seems to rely more on the basal ganglia.…”

Section: Discussionsupporting

confidence: 92%

“…By contrast, there is evidence that the gradual acquisition of probabilistic contingencies depends more heavily on subcortical structures in the basal ganglia, and less on cortical structures (Knowlton et al 1996;Seger and Cincotta 2005). The results of multiple studies (Keri et al 2000;Weickert et al 2002;Beninger et al 2003;Keri et al 2005) suggest that the acquisition of probabilistic contingencies in schizophrenia patients may be relatively unimpaired, perhaps indicative of a relatively intact basal ganglia function in schizophrenia. Thus, patients with SZ could show intact initial discrimination learning, but impaired reversal learning.…”

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confidence: 99%

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Probabilistic reversal learning impairments in schizophrenia: Further evidence of orbitofrontal dysfunction

Waltz

Gold

2007

Schizophrenia Research

310

257

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Impairments in feedback processing and reinforcement learning appear to be prominent aspects of schizophrenia (SZ), which may relate to symptoms of the disorder. Evidence from cognitive neuroscience investigations indicates that disparate brain systems may underlie different kinds of feedback-driven learning. The ability to rapidly shift response tendencies in the face of negative feedback, when reinforcement contingencies are reversed, is an important type of learning thought to depend on ventral prefrontal cortex (PFC). Schizophrenia has long been associated with dysfunction in dorsolateral areas of PFC, but evidence for ventral PFC impairment in more mixed. In order to assess whether SZ patients experience particular difficulty in carrying out a cognitive function commonly linked to ventral PFC function, we administered to 34 patients and 26 controls a modified version of an established probabilistic reversal learning task from the experimental literature (Cools et al. 2002). Although SZ patients and controls performed similarly on the initial acquisition of probabilistic contingencies, patients showed substantial learning impairments when reinforcement contingencies were reversed, achieving significantly fewer reversals [Χ^2(6)=15.717, p=0.008]. Even when analyses were limited to subjects who acquired all probabilistic contingencies initially (22 patients and 20 controls), patients achieved significantly fewer reversals [Χ^2(3)=9.408, p=0.024]. These results support the idea that ventral PFC dysfunction is a prevalent aspect of schizophrenic pathophysiology, which may contribute to deficits in reinforcement learning exhibited by patients. Further studies are required to investigate the roles of dopaminergic systems in these impairments. Keywordsschizophrenia; dopamine; reinforcement; basal ganglia; prefrontal; orbitofrontal One of the most common neuropsychological findings in the schizophrenia (SZ) literature is that of impaired attentional set-shifting, as evidenced by studies using tasks like the Wisconsin Card Sort Test (WCST) and the intradimensional/extradimensional (ID/ED) attentional setshifting task. This deficit has often been linked to dysfunction of dorsolateral prefrontal cortex (DLPFC), one of the most frequently-observed neural correlates of schizophrenia (Weinberger et al. 1986;Berman et al. 1988). One possible source of set-shifting deficits in patients may be set-learning impairments related to limitations in DLPFC-dependent attentional and working memory resources. Another possible source of set-shifting difficulties, however, may be a specific impairment in reversing learned associations. The reversal of learned associations is known to depend on ventral and medial areas of prefrontal cortex (PFC) from a variety of studies involving both human and nonhuman animal subjects, including both lesion studies (Dias et al. 1996;Fellows and Farah 2003;Hornak et al. 2004) and those using physiological Corresponding Author: Dr. James Andrew Waltz, PhD, Maryland Psychiatric Research Center Pu...

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Section: Discussionsupporting

confidence: 92%

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confidence: 99%

Probabilistic reversal learning impairments in schizophrenia: Further evidence of orbitofrontal dysfunction

Waltz

Gold

2007

Schizophrenia Research

310

257

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“…Priming has also been obtained in schizophrenia with a variety of other procedural tests, such as serial reaction time, where the subjects press one of four keys corresponding to stimuli that appears in one (of four) positions on a screen (Green, Kern, & Williams, 1997); or on a probabilistic classification task, in which subjects decide whether a set of four geometrical shapes are predictive of hypothetical weather conditions of rain or sunshine (Keri et al, 2000). All these studies found a dissociation effect.…”

Section: Palabras Clave: Facilitación Memoria Implícita Esquizofrenmentioning

confidence: 99%

A Comparison of Implicit Memory Tests in Schizophrenic Patients and Normal Controls

et al. 2007

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The objective of the current study was to compare the performance of schizophrenic patients and normal controls on implicit memory tests. Two neuropsychological tasks were administered to 29 patients and normal participant samples. The implicit tests were: Word fragment completion and Word production from semantic categories. The priming score was the variable of interest. Priming effects are obtained in normal subjects and schizophrenia patients, regardless of the implicit test used. However, a dissociation in priming between normal and patient groups was observed, depending on the test used. For word fragment test, priming was identical between the two groups. However, for word production, priming obtained in schizophrenics was lower than priming in normal controls. Results confirm a dissociation effect in implicit memory tests. These results could be explained in the context of the Roediger and Blaxton (1987) distinction between data-driven and conceptually-driven processing. This evidence suggests that a complete neuropsychological assessment of memory in schizophrenia should include different kinds of implicit memory tests (procedural, perceptual, and conceptual tasks). Keywords: priming, implicit memory, schizophrenia, memory impairmentEl objetivo de este estudio fue comparar la ejecución de pacientes esquizofrénicos y controles no clínicos en tests de memoria implícita. Se administraron dos pruebas neuropsicológicas a una muestra de 29 pacientes y a dos muestras de participantes no clínicos. Los tests implícitos fueron: Completar fragmentos de palabras y Generación de ejemplares de categorías semánticas. La variable de interés fue la facilitación. Los efectos de facilitación se obtienen en sujetos no clínicos y en pacientes esquizofrénicos, independientemente del test implícito que se utilice. Sin embargo, se ha observado una disociación en la facilitación entre grupos de controles y pacientes, dependiendo del test utilizado. En tests de fragmentos de palabras la facilitación es idéntica en los dos grupos. Sin embargo, en producción de palabras, la facilitación obtenida en esquizofrénicos es menor que la facilitación en controles. Los resultados confirman la existencia de un efecto disociativo en tests de memoria implícita. Estos resultados podrían explicarse en el contexto de la distinción de Roediger y Blaxton (1987) entre procesamiento guiado por los datos y procesamiento guiado conceptualmente. Esta evidencia sugiere que la evaluación neuropsicológica de la memoria en la esquizofrenia debería incluir distintos tipos de pruebas de memoria implícita (procedimentales, perceptuales, y conceptuales). Palabras clave: facilitación, memoria implícita, esquizofrenia, daños en memoria

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“…These results have been inter-preted as supporting the claim that there are separate memory systems for declarative memory (in the medial temporal lobes) and nondeclarative learning (in the basal ganglia). Other studies of the weather prediction task have demonstrated severe impairments in patients with schizophrenia (Keri et al 2000; T. Weickert, T. Goldberg, A. Terrazas, L. Bigelow, J. Malley, M. Egan, and D. Weinberger, in prep.). Functional brain imaging by Poldrack and colleagues has shown that the medial temporal lobes become active early during learning of the weather-prediction task, and gradually become deactivated as the task is learned; conversely, the basal ganglia are inactive early in learning, but gradually become active (Poldrack et al 1999(Poldrack et al , 2001).…”

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confidence: 96%

How do People Solve the “Weather Prediction” Task?: Individual Variability in Strategies for Probabilistic Category Learning

Gluck

Shohamy²,

Myers³

2002

Learn. Mem.

227

354

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Probabilistic category learning is often assumed to be an incrementally learned cognitive skill, dependent on nondeclarative memory systems. One paradigm in particular, the weather prediction task, has been used in over half a dozen neuropsychological and neuroimaging studies to date. Because of the growing interest in using this task and others like it as behavioral tools for studying the cognitive neuroscience of cognitive skill learning, it becomes especially important to understand how subjects solve this kind of task and whether all subjects learn it in the same way. We present here new experimental and theoretical analyses of the weather prediction task that indicate that there are at least three different strategies that describe how subjects learn this task. (1) An optimal multi-cue strategy, in which they respond to each pattern on the basis of associations of all four cues with each outcome; (2) a one-cue strategy, in which they respond on the basis of presence or absence of a single cue, disregarding all other cues; or (3) a singleton strategy, in which they learn only about the four patterns that have only one cue present and all others absent. This variability in how subjects approach this task may have important implications for interpreting how different brain regions are involved in probabilistic category learning.

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Schizophrenics know more than they can tell: probabilistic classification learning in schizophrenia

Abstract: Patients with schizophrenia were able to establish representations of complex categories, but these remained unconscious. This is consistent with earlier reports, suggesting damaged explicit and spared implicit memory in schizophrenia.

Cited by 74 publications

References 35 publications

Probabilistic reversal learning impairments in schizophrenia: Further evidence of orbitofrontal dysfunction

Probabilistic reversal learning impairments in schizophrenia: Further evidence of orbitofrontal dysfunction

A Comparison of Implicit Memory Tests in Schizophrenic Patients and Normal Controls

How do People Solve the “Weather Prediction” Task?: Individual Variability in Strategies for Probabilistic Category Learning

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