Implicit learning of nonlocal musical rules: implicitly learning more than chunks

Dominant theories of implicit learning assume that implicit learning merely involves the learning of chunks of adjacent elements in a sequence. In the experiments presented here, participants implicitly learned a nonlocal rule, thus suggesting that implicit learning can go beyond the learning of chunks. Participants were exposed to a set of musical tunes that were all generated using a diatonic inversion. In the subsequent test phase, participants either classified test tunes as obeying a rule (direct test) or rated their liking for the tunes (indirect test). Both the direct and indirect tests were sensitive to knowledge of chunks. However, only the indirect test was sensitive to knowledge of the inversion rule. Furthermore, the indirect test was overall significantly more sensitive than the direct test, thus suggesting that knowledge of the inversion rule was below an objective threshold of awareness.     

Spatial frequency processing in schizophrenia: trait or state marker?

B. F. O'Donnell et al. found impaired discrimination performances at low and medium spatial frequencies in patients with schizophrenia. In this study, the authors replicated this finding in a group of remitted, unmedicated, and highly functioning outpatients with spared IQ and attentional functions. However, the deficit was restricted to low spatial frequencies (0.5 cycles/degree), which suggests that this deficit is a trait marker of schizophrenia.     

Motion integration during motion aftereffects

The perceived global motion of a stimulus depends on how its different local motion-direction vectors are distributed in space and time. When they are explicitly co-localized, as in the case of locally paired motion, competitive motion integration mechanisms produce a unitary global motion direction determined by their vector average. During motion aftereffects induced by simultaneous adaptation to multiple motion directions, just as in the case of locally paired motion, different directional signals originate simultaneously from exactly the same position in space. Therefore, the perceived global motion direction during motion aftereffects results from local vector averaging of the co-localized motion-direction signals induced by adaptation.     

Categories, prototypes and memory systems in Alzheimer's disease

Recent studies indicate that category learning is mediated by multiple neuronal systems. It has been shown that patients with marked impairments in executive functions, explicit memory and procedural learning can categorize the exemplars and prototype of a previously trained category. Simple, self-organizing neuronal networks can explain prototype learning and related dysfunctions in Alzheimer's disease, and provide a model of how prototype learning is mediated by circumscribed mechanisms in the visual cortex.     

Alcohol increases hypnotic susceptibility

One approach to hypnosis suggests that for hypnotic experience to occur frontal lobe activity must be attenuated. For example, cold control theory posits that a lack of awareness of intentions is responsible for the experience of involuntariness and/or the subjective reality of hypnotic suggestions. The mid-dorso-lateral prefrontal cortex and the ACC are candidate regions for such awareness. Alcohol impairs frontal lobe executive function. This study examined whether alcohol affects hypnotisability. We administered 0.8 mg/kg of alcohol or a placebo to 32 medium susceptible participants. They were subsequently hypnotised and given hypnotic suggestions. All participants believed they had received some alcohol. Participants in the alcohol condition were more susceptible to hypnotic suggestions than participants in the placebo condition. Impaired frontal lobe activity facilitates hypnotic responding, which supports theories postulating that attenuation of executive function facilitates hypnotic response, and contradicts theories postulating that hypnotic response involves enhanced inhibitory, attentional or other executive function.     

Psychopathological Symptom Dimensions in Patients with Gastrointestinal Disorders

The current study aims to investigate the factorial validity of a widely used psychopathological rating scale, the Symptom Check List-90-R (SCL-90-R), in a group of patients suffering from gastrointestinal disorders, and to determine the specific psychopathological profiles that characterize the individual patient subgroups. Patients suffering from either irritable bowel syndrome, ulcerative colitis, non-erosive reflux disease or erosive reflux disease completed the SCL-90-R at a tertiary care gastroenterology department. Seven factors were identified, with one major distress factor and six minor factors. Comparison of the gastrointestinal disorder subgroups indicated that irritable bowel syndrome patients exhibited significantly more psychological distress compared to the other groups, and that gastrointestinal patients as a group, compared to healthy controls, were characterized by high levels of irritable depression and somatization. In planning further studies we encourage the use of factors identified in our study. The treatment of substantial irritable depression can be an important factor in improving quality of life in patients suffering from gastrointestinal disorders.     

The conscious, the unconscious, and familiarity

This article examines the role of subjective familiarity in the implicit and explicit learning of artificial grammars. Experiment 1 found that objective measures of similarity (including fragment frequency and repetition structure) predicted ratings of familiarity, that familiarity ratings predicted grammaticality judgments, and that the extremity of familiarity ratings predicted confidence. Familiarity was further shown to predict judgments in the absence of confidence, hence contributing to above-chance guessing. Experiment 2 found that confidence developed as participants refined their knowledge of the distribution of familiarity and that differences in familiarity could be exploited prior to confidence developing. Experiment 3 found that familiarity was consciously exploited to make grammaticality judgments including those made without confidence and that familiarity could in some instances influence participants' grammaticality judgments apparently without their awareness. All 3 experiments found that knowledge distinct from familiarity was derived only under deliberate learning conditions. The results provide decisive evidence that familiarity is the essential source of knowledge in artificial grammar learning while also supporting a dual-process model of implicit and explicit learning.     

Implicit synthesis

In this reply to Neal and Hesketh and to the commentators, we argue that implicit knowledge is partly abstract and can be usefully defined by the criteria of both metaknowledge and intentional control. We suggest that the pattern of dissociations supports a claim of separate implicit and explicit learning modes. According to our characterization, implicit learning leads to knowledge that is not automatically represented as knowledge by the learning process; instead, the presence of knowledge has to be inferred by the subject (partial explicitation) if metaknowledge is gained at all. During explicit learning, knowledge is automatically labeled as knowledge by the learning process, so that metaknowledge comes immediately and to the fullest extent. Finally, we suggest that implicit knowledge may to some degree apply regardless of intention.