Learning and production of movement sequences: behavioral, neurophysiological, and modeling perspectives

A wave of recent behavioral studies has generated a new wealth of parametric observations about serial order behavior. What was a trickle of neurophysiological studies has grown to a steady stream of probes of neural sites and mechanisms underlying sequential behavior. Moreover, simulation models of serial behavior generation have begun to open a channel to link cellular dynamics with cognitive and behavioral dynamics. Here we review major results from prominent sequence learning and performance tasks, namely immediate serial recall, typing, 2 x N, discrete sequence production, and serial reaction time. These tasks populate a continuum from higher to lower degrees of internal control of sequential organization and probe important contemporary issues such as the nature of working-memory representations for sequential behavior, and the development and role of chunks in hierarchical control. The main movement classes reviewed are speech and keypressing, both involving small amplitude movements amenable to parametric study. A synopsis of serial order models, vis-a-vis major empirical findings leads to a focus on competitive queuing (CQ) models. Recently, the many behavioral predictive successes of CQ models have been complemented by successful prediction of distinctively patterned electrophysiological recordings. In lateral prefrontal cortex, parallel activation dynamics of multiple neural ensembles strikingly matches the parallel dynamics predicted by CQ theory. An extended CQ simulation model--the N-STREAMS neural network model--exemplifies ongoing attempts to accommodate a broad range of both behavioral and neurobiological data within a CQ-consistent theory.     

Dual diagnosis in an Australian forensic psychiatric hospital: prevalence and implications for services

Despite a growing awareness of the unique needs of psychiatric patients with co-occurring substance abuse and dependence disorders (i.e. dual diagnosis), there is a dearth of research investigating the prevalence of dual diagnosis in forensic psychiatric populations. Similarly, little work has been done to determine the implications of dual diagnosis for forensic psychiatric patients. Patients at the Thomas Embling Hospital in Victoria, Australia, were assessed to determine the prevalence of substance abuse disorders and mental illnesses within this population. Results reveal that the majority of patients (approximately 74%) have a lifetime substance abuse or dependence disorder. Information was collected concerning patients' criminal histories and the Level of Service Inventory, Revised, was completed for each patient who participated. Results suggest that patients with both major mental illnesses and substance abuse disorders have more extensive criminal histories and demonstrate a higher level of risks and needs when compared with patients with major mental illness alone. The implications for the development and delivery of effective forensic mental health services that address both co-occurring disorders are also discussed.     

The relationships among clinical depression, suicide, and other actions that may hasten death

Clinical depression and other psychological disorders have been associated with suicidal ideation, attempts, and deaths. Because of the link between suicide and mental illness, whenever discussion of "assisted suicide" arises, the possibility that major depression is affecting the decision arises. This article examines the literature on clinical depression as it relates to suicide, "assisted suicide," and other decisions that will hasten death (i.e. withholding and withdrawing treatment, terminal sedation, and voluntarily stopping eating and drinking). Ethical and legal considerations when working with individuals who are considering taking an action that would hasten death are also briefly reviewed. The article ends with practice and policy recommendations.     

Assessing risk for violence among male and female civil psychiatric patients: the HCR-20, PCL:SV, and VSC

This study evaluated the predictive validity of violence risk assessments conducted using the HCR-20, the Psychopathy Checklist: Screening Version (PCL:SV), and by the Violence Screening Checklist (VSC) in a sample of 268 involuntarily hospitalized male and female psychiatric patients. Information pertaining to violence and crime was coded from medical charts and correctional records. The HCR-20/PCL:SV evidenced modest non-significant associations in postdictive assessments of inpatient violence among men. Moderate to strong significant associations were found between the HCR-20/PCL:SV and inpatient violence among women. Pseudo-prospective assessments using the HCR-20 and PCL:SV resulted in moderate to large relationships with violence and crime in men and women following community discharge. It is concluded that the VSC is a promising tool for assessing acute inpatient violence risk with men. Findings offer preliminary validation of the predictive validity of the HCR-20 and PCL:SV with female civil psychiatric patients.     

Assessing the distinguishability of models and the informativeness of data

A difficulty in the development and testing of psychological models is that they are typically evaluated solely on their ability to fit experimental data, with little consideration given to their ability to fit other possible data patterns. By examining how well model A fits data generated by model B, and vice versa (a technique that we call landscaping), much safer inferences can be made about the meaning of a model's fit to data. We demonstrate the landscaping technique using four models of retention and 77 historical data sets, and show how the method can be used to: (1) evaluate the distinguishability of models, (2) evaluate the informativeness of data in distinguishing between models, and (3) suggest new ways to distinguish between models. The generality of the method is demonstrated in two other research areas (information integration and categorization), and its relationship to the important notion of model complexity is discussed.     

Category specificity in normal episodic learning: applications to object recognition and category-specific agnosia

Studies of patients with category-specific agnosia (CSA) have given rise to multiple theories of object recognition, most of which assume the existence of a stable, abstract semantic memory system. We applied an episodic view of memory to questions raised by CSA in a series of studies examining normal observers' recall of newly learned attributes of familiar objects. Subjects first learned to associate arbitrarily assigned colors or textures to objects in a training phase, and then attempted to report the newly learned attribute of each object in a recall task. Our subjects' pattern of recall errors was similar both quantitatively and qualitatively to the identification deficits among patients with CSA for biological objects. Furthermore, errors tended to reflect conceptually and structurally based confusions. We suggest that object identification involves recruitment and integration of information across distributed episodic memories and that this process is susceptible to interference from objects that are structurally similar and conceptually related.     

An application of item response theory analysis to alcohol, cannabis, and cocaine criteria in DSM-IV

Item response theory (IRT) is supplanting classical test theory as the basis for measures development. This study demonstrated the utility of IRT for evaluating DSM-IV diagnostic criteria. Data on alcohol, cannabis, and cocaine symptoms from 372 adult clinical participants interviewed with the Composite International Diagnostic Interview--Expanded Substance Abuse Module (CIDI-SAM) were analyzed with Mplus (B. Muthen & L. Muthen, 1998) and MULTILOG (D. Thissen, 1991) software. Tolerance and legal problems criteria were dropped because of poor fit with a unidimensional model. Item response curves, test information curves, and testing of variously constrained models suggested that DSM-IV criteria in the CIDI-SAM discriminate between only impaired and less impaired cases and may not be useful to scale case severity. IRT can be used to study the construct validity of DSM-IV diagnoses and to identify diagnostic criteria with poor performance.     

The explicit and implicit dance in psychoanalytic change

How the implicit/non-declarative and explicit/declarative cognitive domains interact is centrally important in the consideration of effecting change within the psychoanalytic arena. Stern et al. (1998) declare that long-lasting change occurs in the domain of implicit relational knowledge. In the view of this author, the implicit and explicit domains are intricately intertwined in an interactive dance within a psychoanalytic process. The author views that a spirit of inquiry (Lichtenberg, Lachmann & Fosshage 2002) serves as the foundation of the psychoanalytic process. Analyst and patient strive to explore, understand and communicate and, thereby, create a 'spirit' of interaction that contributes, through gradual incremental learning, to new implicit relational knowledge. This spirit, as part of the implicit relational interaction, is a cornerstone of the analytic relationship. The 'inquiry' more directly brings explicit/declarative processing to the foreground in the joint attempt to explore and understand. The spirit of inquiry in the psychoanalytic arena highlights both the autobiographical scenarios of the explicit memory system and the mental models of the implicit memory system as each contributes to a sense of self, other, and self with other. This process facilitates the extrication and suspension of the old models, so that new models based on current relational experience can be gradually integrated into both memory systems for lasting change.     

Systematic application and removal of protective equipment in the assessment of multiple topographies of self-injury

We evaluated the effects of systematic application and removal of protective equipment on three topographies of self-injurious behavior (SIB) exhibited by a girl who had been diagnosed with autism. Results showed that when protective equipment was applied, SIB decreased to near-zero levels. In addition, withdrawal of protective equipment for specific topographies of SIB (by removing only the corresponding padding) increased rates of SIB only for that topography of SIB. Next, a functional analysis of hand SIB showed that protective equipment suppressed this behavior in all conditions and that the behavior was maintained by automatic reinforcement when padding was removed. Results are discussed in terms of sensory extinction as a possible mechanism responsible for response suppression.