基于知觉的恐惧泛化的认知神经机制

恐惧泛化是条件性恐惧反应转移到另一个相似但安全的刺激的现象。适当的恐惧泛化对人类有积极意义, 而过度的恐惧泛化则不利于个体有效地适应环境。基于知觉的恐惧泛化研究揭示了恐惧泛化的规律, 因而被广泛应用。本文首先梳理了对知觉恐惧泛化的相关研究, 介绍恐惧泛化的经典理论基础—巴普洛夫条件反射以及恐惧泛化梯度; 其次简要回顾基于多个感觉通道(即视觉、听觉、情景)的知觉恐惧泛化研究现状; 再次, 分别对海马、杏仁核、脑岛和前额叶等脑区在恐惧泛化中的作用进行回顾, 进一步总结出恐惧泛化的神经环路结构模型。最后, 简要区分了基于知觉的恐惧泛化和正在兴起的基于概念的恐惧泛化, 进而指出未来研究需要结合基于概念的恐惧泛化、区分被试对刺激的辨别力、增加恐惧刺激材料的准确性及多样化、结合激素等个体差异和多模态脑成像数据来展开。     

Impaired discriminative fear-conditioning resulting from elevated fear responding to learned safety cues among individuals with panic disorder

Classical fear-conditioning is central to many etiologic accounts of panic disorder (PD), but few lab-based conditioning studies in PD have been conducted. One conditioning perspective proposes associative-learning deficits characterized by deficient safety learning among PD patients. The current study of PD assesses acquisition and retention of discriminative aversive conditioning using a fear-potentiated startle paradigm. This paradigm was chosen for its specific capacity to independently assess safety- and danger learning in the service of characterizing putative anomalies in each type of learning among those with PD. Though no group difference in fear-potentiated startle was found at retention, acquisition results demonstrate impaired discriminative learning among PD patients as indexed by measures of conditioned startle-potentiation to learned safety and danger cues. Importantly, this discrimination deficit was driven by enhanced startle-potentiation to the learned safety cue rather than aberrant reactivity to the danger cue. Consistent with this finding, PD patients relative to healthy individuals reported higher expectancies of dangerous outcomes in the presence of the safety cue, but equal danger expectancies during exposure to the danger cue. Such results link PD to impaired discrimination learning, reflecting elevated fear responding to learned safety cues.     

More is more: The relationship between vocabulary size and word extension

This study experimentally tested the relationship between children’s lexicon size and their ability to learn new words within the domain of color. We manipulated the size of 25 20-month-olds’ color lexicons by training them with two, four, or six different color words over the course of eight training sessions. We subsequently tested children’s ability to extend new color words to new instances. We found that training with a broader number of color words led to increased extension of new words. The results suggest that children’s learning history predicts their ability to learn new words within domains.     

A DIRECT PROMPTING STRATEGY FOR INCREASING RECIPROCAL INTERACTIONS BETWEEN HANDICAPPED AND NONHANDICAPPED SIBLINGS

We investigated the effects of a sibling training procedure, consisting of direct prompting and modeling, on the occurrence of reciprocal interactions between nonhandicapped and handicapped siblings. Data were obtained for training, generalization, and follow-up. Results of a multiple-baseline design across three pairs of siblings showed that: (a) direct prompting of interactions was an effective strategy for increasing reciprocal interactions between handicapped and nonhandicapped siblings; (b) the training procedure resulted in increased levels of initiations and responsiveness to initiations; (c) reciprocal interactions between siblings generalized to larger play groups or across settings; (d) reciprocal interactions between handicapped subjects and untrained, nonhandicapped peers increased without direct training; (e) the siblings' levels of interactions were maintained at 6 mo follow-up; and (f) these findings were judged socially valid by the siblings' parents.     

TRAINED,GENERALIZED, AND COLLATERAL BEHAVIOR CHANGES OF PRESCHOOL CHILDREN RECEIVING GROSS-MOTOR SKILLS TRAINING

Three preschool children participated in a behavioral training program to improve their gross-motor skills. Ten target behaviors were measured in the training setting to assess direct effects of the program. Generalization probes for two gross-motor behaviors, one fine-motor skill, and two social behaviors were conducted in other settings. Results indicated that the training program improved the gross-motor skills trained and that improvements sometimes generalized to other settings. Contrary to suggestions in educational literature, the gross-motor training program did not produce changes in fine-motor skills or social behaviors. Implications for educators and for the development of the technology of generalization are outlined.     

SOME DIRECT AND GENERALIZED EFFECTS OF REPLACING AN AUTISTIC MAN'S ECHOLALIA WITH CORRECT RESPONSES TO QUESTIONS

We extended the use of operant procedures to decrease immediate echolalia and increase the appropriate responding to questions of a 21-year-old autistic man. Three experiments were conducted in which the overall plan was to (a) encourage the subject to remain quiet before, during, and after the presentation of questions and (b) teach him to use environmental cues (i.e., word cards or a model's responses) to increase the likelihood of responding correctly. Multiple baseline designs demonstrated that echolalia was rapidly replaced with correct stimulus-specific responses. In addition, there were a variety of generalized improvements in the subject's verbal responses to questions. The procedures and results are contrasted to previous research in an attempt to explain the encouraging findings.     

Generalization peak shift for autoshaped and operant key pecks.

Pigeons acquired discriminated key pecking between 528- and 540-nm stimuli by either a response-reinforcer (operant group) or a stimulus-reinforcer (autoshaped group) contingency, with other training-schedule parameters comparable over groups. For the birds in the operant group, key pecks intermittently produced grain in the presence of one hue on the key (positive stimulus) but not in the other (negative stimulus). For the birds in the autoshaped group, pecking emerged when grain was intermittently presented independently of key pecking during one key color but was not presented during the other key color. Two independent contingency assays, peck-location comparisons and elimination of differences in reinforcement rate, confirmed the effectiveness of the two training procedures in establishing operant or respondent control of key pecking. After reaching a 10:1, or better, discrimination ratio between key pecks during the two key colors, the birds received a wavelength generalization test. Criterion baseline key-peck rates were comparable for operant and autoshaped groups prior to testing. On the generalization test, performed in extinction, all birds pecked most at a stimulus removed from the positive training stimulus in the direction away from the negative stimulus. In testing, autoshaped "peak" rates (24.5 to 64.9 pecks per minute) were from 33% to 80% higher than rates in the presence of the training stimuli. Respondent peak shift rarely has been reported heretofore, and never this consistently and robustly. These results further confirm the similarity of perceptual processing in classical and operant learning. They are discussed in terms of Spence's gradient-interaction theory and Weiss' (1978) two-process model of stimulus control.     

Using videotape modeling to facilitate generalized purchasing skills

Six students with moderate and severe disabilities were taught generalized purchasing skills through the use of videotape modeling in one, two, or three stores and in vivo instruction within one store. Training was conducted within three orders of treatments: (a) in vivo instruction followed by videotape training, (b) videotape training followed by in vivo instruction, and (c) concurrent videotape and in vivo instruction. Generalization probes were conducted in stores that were the same as those modeled on videotape, untrained stores that were infrequently probed (and never modeled on tape or taught directly), and novel stores that were probed only once after training. Results indicated the production of generalized purchasing skills by the students who received concurrent training and by the students who received sequential training. Videotape and in vivo training in isolation did not lead to generalized shopping skills. The results are discussed in terms of investigating the possible role of verbalization during videotape training on generalized responding and the effects of multiple probe interventions on inadvertent learning of critical skills.deceased.     

ACQUISITION AND CROSS-SETTING GENERALIZATION OF MANUAL SIGNS WITH SEVERELY RETARDED INDIVIDUALS

In this study, we assessed the effect of a transfer of stimulus control procedure on the acquisition and cross-setting generalization of manual signs with four profoundly retarded individuals. Two individuals were trained to produce appropriate signs to verbal instructions, whereas the other two were trained until manual signs were controlled by visual stimuli (objects). Data obtained from three probe situations (two for one individual) constituted the dependent variables of the investigation. The results, gathered within a multiple-baseline design across signs showed that (a) individuals acquired the trained signs and (b) maintenance and generalization across settings (classroom, ward) and persons (teachers, ward staff) occurred, but was highly variable between and within individuals.     

AN INSTITUTIONAL STAFF TRAINING AND SELF-MANAGEMENT PROGRAM FOR DEVELOPING MULTIPLE SELF-CARE SKILLS IN SEVERELY/PROFOUNDLY RETARDED INDIVIDUALS

Although considerable attention has been given to the development of institutional staff training and management programs, the generalized effects of such programs on staff and resident behavior have seldom been examined. This study evaluated a program for teaching institutional staff behavioral training and self-management skills during self-care teaching sessions with severely and profoundly retarded residents. Following baseline observations in three self-care situations (toothbrushing, haircombing, handwashing), four direct care staff were sequentially taught to use verbal instruction, physical guidance, and contingent reinforcement in the toothbrushing program. During maintenance, staff were simultaneously taught to record, graph, and evaluate resident and their own behavior in the toothbrushing sessions. Staff were taught use of the training and self-management skills through a sequence of written instructions, videotaped and live modeling, rehearsal, and videotaped feedback. Observer presence and experimenter supervision were gradually decreased during the maintenance condition. Results indicated that during training and maintenance staff: (a) learned to use the training skills appropriately and consistently in the example situation (toothbrushing); (b) applied the skills in the generalization situations (haircombing and handwashing); and thereafter (c) maintained consistent and appropriate use of the skills with infrequent supervision. In addition, important changes in retarded residents' independent self-care responding occurred as staff training skills developed. Results are discussed in terms of their implication for future research and continued development of effective staff training and management programs.