Biomedical subjects

Giuseppe Pellizzer

Publications and source records attributed to Giuseppe Pellizzer.

4 recordsLinked to original sources

PubMed2006

Computerized binary scale of auditory speech hallucinations (cbSASH).

BACKGROUND: Evidence indicates that the neuropathology of auditory verbal hallucinations (AVH) varies according to their phenomenological characteristics. Therefore, AVH should be subgrouped accordingly in hallucinations research. As evaluation of these characteristics depends entirely on the patient report, obtaining measurement of the reliability of these reports is crucial. METHOD: A computerized binary scale of auditory speech hallucinations (cbSASH) was developed to evaluate the phenomenology of AVH. It includes two subscales (inconsistency and malingering) to assess the reliability of the patient report. The cbSASH was administered along with MMPI-2, a general psychopathology scale, which includes similar validity subscales. Thirty-four psychotic patients with history of AVH were enrolled in this study. RESULTS: The scores on the inconsistency and malingering subscales of the cbSASH were correlated with the scores on the corresponding validity subscales in the MMPI-2. The combination of the malingering and inconsistency subscales provided robust measures of the reliability and ability of the patients' descriptions of their hallucinations. CONCLUSION: The cbSASH provides a reliable and comprehensive evaluation of the phenomenology of AVH. Consequently, it is possible to subgroup patients according to the characteristics of their hallucinations. This refinement of AVH phenotypes could reduce the noise and inconsistency noted in AVH and psychosis research.

Adult↗

PubMed2006

Time-dependent effects of discrete spatial cues on the planning of directed movements.

The degree of preparation of a motor response varies with the information available regarding the response that will need to be executed and with the time provided to process that information. In experiment 1 we investigated the time-course of processing the information specified by discrete spatial cues regarding the upcoming target of directed movements. For this purpose we varied the number of cues that indicated the possible locations of the target and the duration of the cue period preceding the target. The results showed that the effects of processing the information provided by the cues developed progressively and stabilized after 0.2 s. In addition, the level of motor preparation reached was a function of number of cues. However, the effect of number of cues occurred even in the no cue period condition, i.e. when subjects could not have benefited from the information provided by the cues to prepare the response. Further analyses suggested the hypothesis that, in the no cue period condition, the effect of number of cues resulted from the cues acting as distractors (i.e., interference) whereas, with longer cue periods, the effect resulted from the motor preparatory process (i.e., facilitation). This hypothesis was tested in experiment 2 where the number of cues and the number of distractors were varied inversely. Cues and distractors were the same type of stimuli and differed only in their relation to the time of presentation of the target. Subjects performed in a directed response task and in a control detection task. It was predicted that the facilitatory effect of the cues and the interference effect of the distractors on the planning of the directed response would oppose each other and produce a non-monotonic change of RT across conditions. The results conformed to the prediction and, therefore, supported the hypothesis of independent effects of facilitation and interference. In addition, we found that the pattern of RT across conditions in the detection task differed radically with that in the directed response task. This result indicates that the time-dependent effects of cues and distractors are contingent on the type of motor response required in the task, and, in particular on the spatial requirement on the motor response.

Adult↗

PubMed2003

Motor planning: effect of directional uncertainty with continuous spatial cues.

We have investigated the effect of directional uncertainty on the planning of reaching movements. For this purpose, we have used sections of annuli as spatial cues to indicate the directional range within which the target would be presented. The results showed that the reaction time of the reaching response increased with cue range and with the angle between the center of the cue and the target. In addition, the initial direction of movement was biased toward the center of the cue. These results conformed to the predictions of the capacity-sharing model. This model assumes that the processing resources used for motor planning are limited and distributed as a function of the range of directions indicated by the cue, and that when the target appears, these resources are reallocated to represent the response to be executed.

Adult↗

PubMed2003

Motor planning: effect of directional uncertainty with discrete spatial cues.

We investigated the effect of spatial uncertainty on motor planning by using the cueing method in a reaching task (experiment 1). Discrete spatial cues indicated the different locations in which the target could be presented. The number of cues as well as their direction changed from trial to trial. We tested the adequacy of two models of motor planning to account for the data. The switching model assumes that only one motor response can be planned at a time, whereas the capacity-sharing model assumes that multiple motor responses can be planned in parallel. Both models predict the same relation between average reaction time (RT) and number of cues, but they differ in their prediction of the shape of the distribution of the reaction time. The results showed that RT increased with the number of cues independently from their spatial dispersion. This relation was well described by the function predicted by both models, whereas it was poorly described by the Hick-Hyman law. In addition, the distribution of RT conformed to the prediction of the capacity-sharing model and not to that of the switching model. We investigated the role that the requirement of a spatially directed motor response might have had on this pattern of results by testing subjects in a simple RT task (experiment 2) with the same cueing presentation as in experiment 1. The results contrasted with those in experiment 1 and showed that RT was dependent on the spatial dispersion of the cues and not on their number. The results of the two experiments suggest that the mode of processing of potential targets is dependent on the spatial constraints of the task. The processing resources can be either divided relative to the spatial distribution of possible targets or across multiple independent discrete representations of these targets.

Adult↗