Adaptation to Reversal of Retinal Feedback of Eyemovements

Both optical and hybrid-computer methods were devised to reverse the visual feedback which the eye gets of its own movements. Optical reversal by a contact lens device caused persisting, unstable, skittered, blurred vision, to which the subject made no effective adaptation. Using a hybrid analog-digital-analog computer, eyemovement-retinal feedback was reversed by yoking oscilloscope targets to the transduced electrical signals of ocular movements and reversing the sign of input-output control of the computer system. Vision with such computer-reversed feedback from ocular movements duplicated the experiences with the contact-lens method. Practice over five sessions of 50 trials indicated that three Ss showed no significant improvement in eye-tracking accuracy with the reversed vision. Perception of direction in vision and the basic signal processes of vision were thus found to be dependent on built-in direction specificity of eyemovement-retinal feedback interactions which also govern dynamic specialization and control of pursuit, saccadic, and fixation movements.     

Adaptation to a Nonlinear Visuomotor Amplitude Transformation With Continuous and Terminal Visual Feedback

The control of a cursor on a computer monitor offers a simple means of exploring the limits of the plasticity of human visuomotor coordination. The authors explored the boundary conditions for adaptation to nonlinear visuomotor amplitude transformations. The authors hypothesized that only with terminal visual feedback during practice, but not with continuous visual feedback, humans might develop an internal model of the nonlinear visuomotor amplitude transformation. Thus, 2 groups were engaged in a sensorimotor adaptation task receiving either continuous or terminal visual feedback during the practice phase. In contrast to expectations, adaptive shifts and aftereffects observed in visual open-loop tests were linearly related to target amplitudes for both groups. Although the 2 feedback groups did not differ with respect to adaptive shifts and aftereffects, terminal visual feedback resulted in stable visual open-loop performance for an extended period, whereas movement errors increased after continuous visual feedback during practice. The benefit of continuous visual feedback, on the other hand, was faster closed-loop performance, indicating an optimization of visual closed-loop control.     

Effects on Prism Adaptation of Duration and Timing of Visual Feedback During Pointing

In two experiments, we investigated the effects of duration of visual feedback of the pointing limb and the time (early to late) in the movement when the limb first becomes visible (timing of visual feedback). Timing, rather than duration of visual feedback, proved to have the greater effect on the relative magnitude of visual and proprioceptive adaptation. Visual adaptation increased smoothly with feedback delay, but corresponding decreases in proprioceptive adaptation underwent an additional sharp change when feedback was delayed until about three-fourths of the way to the terminal limb position. These results are consistent with the idea that visual and proprioceptive adaptation are mediated by exclusive processes. Change in the limb position sense (i.e., proprioceptive adaptation) may be produced by visual guidance of the pointing limb, and view of the limb early in the pointing movement seems to be critical for such visual guidance. The limb may be ballistically “released“ as it nears the terminal position, and, thereafter, any opportunity for visual guidance (i.e., view of the limb) is not effective. On the other hand, change in the eye position sense (i.e., visual adaptation) may be mediated by proprioceptive guidance of the eye; the eyes may track the imaged position of the nonvisible limb. Such proprioceptive guidance seems to be solely a function of the distance moved before the limb becomes visible.     

Effects of Movement Duration and Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement every 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.     

延迟结果反馈对追踪任务技能学习的影响

在运动技能学习中,指导者通过提供外部反馈(Extrinsic feedback),帮助学习者掌握运动技能。结果反馈(knowledge of results,以下简称KR)是人们研究较多的一种追加反馈,它是指根据预定目标提供的关于应答结果的语言化(或可语言化)的末端追加信息(Schrnidt,1988)。     

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed 60 times straight ahead of their nose at a rate of one complete movement every 2 or 3 s, with visual feedback available early in the pointing movement or delayed until the end of the movement. Sagittal pointing was paced such that movement speed covaried with pointing rate. Aftereffect measures (obtained after every 10 pointing trials) showed that when the limb became visible early in a pointing movement, proprioceptive adaptation was greater than visual, but when visual feedback was delayed until the end of the movement, the reverse was true. This effect occurred only with the 3-s pointing rate, however. With the 2-s pointing rate, adaptation was predominately proprioceptive in nature, regardless of feedback availability. Independent of the availability of visual feedback, visual adaptation developed more quickly with 3-s pointing, whereas proprioceptive adaptation developed more rapidly with 2-s pointing. These results are discussed in terms of a model of perceptual-motor organization in which the direction of coordinative (guidance) linkage between eye-head (visual) and hand-head (proprioceptive) systems (and consequently the locus of discordance registration and adaptive recalibration) is determined jointly by pointing rate and feedback availability. An additional effect of pointing rate is to determine the rate of discordant inputs. Maximal adaptive recalibration occurs when the input (pointing) rate matches the time constant of the adaptive encoder in the guided system.     

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

The withdrawal of vision of the arm during a manual aiming task has been found to result in a large increase in aiming error, regardless of the amount of practice in normal vision before its withdrawal. In the present study, the authors investigated whether the increase in error reflects the domination of visual afferent information over the movement representation developed during practice to the detriment of other sources of afferent information or whether it reflects only transformation errors of the location of the target from an allocentric to an egocentric frame of reference. Participants (N = 40) performed aiming movements with their dominant or nondominant arm in a full-vision or target-only condition. The results of the present experiment supported both of those hypotheses. The data indicated that practice does not eliminate the need for visual information for optimizing movement accuracy and that learning is specific to the source or sources of afferent information more likely to ensure optimal accuracy during practice. In addition, the results indicated that movement planning in an allocentric frame of reference might require simultaneous vision of the arm and the target. Finally, practice in a target-only condition, with knowledge of results, was found to improve recoding of the target in an egocentric frame of reference.     

Adaptation to context

Argument theorists often stress the idea of adaptation to context as an alternative to seeing argument as linked propositions. But adaptation is not a clear idea. It is in fact a complicated puzzle. Though many aspects of this puzzle are obscure, one clear conclusion is that the question-answer pair is not a good way to conceptualize adaptation to situation.     

Linking Feedback Quality and Goal Orientation to Feedback Seeking and Job Performance

Contemporary feedback researchers have adopted theoretical perspectives in which personal characteristics interact with aspects of the feedback environment to influence feedback-related perceptions, feedback seeking, and job performance. To test these assertions, this study incorporates implicit person theory, uncertainty reduction theory, and Korman's theory of work motivation (2001) to develop a model that links a critical aspect of the feedback environment (feedback quality) and goal orientation to perceptions of feedback utility, feedback seeking, role clarity, and task performance and organizational citizenship behaviors. Results from supervisor–subordinate dyadic data (N?=?202) obtained from employed students largely support the hypothesized model. Implications are discussed.     

Exposure and Response Prevention and Habit Reversal Training: Commonalities, Differential Use, and Combined Applications

Obsessive-compulsive spectrum disorders (OCSDs) have compulsive (i.e., anxiety reductive) and impulsive (i.e., driven by emotional or involuntary impulses) features. The best established psychological treatments for these disorders are behavioral/cognitive-behavioral in nature. More specifically, exposure and response prevention (ERP) (with or without cognitive therapy) and habit reversal training (HRT) are commonly indicated in the treatment of OCSDs. This paper reviews the use of various components of these therapeutic approaches to treat compulsive and impulsive symptomology in individuals with variants of these disorders. Specifically, ERP monotherapy for compulsive (e.g., obsessive-compulsive, body dysmorphic) and impulsive symptoms (e.g., tics, trichotillomania) is discussed as well as a combined treatment approach that integrates elements of ERP and HRT for individuals displaying mixed symptomology. A case example is also provided that illustrates the successful application of various components of ERP and HRT to treat OCSD symptoms. Lastly, other potential OCSD treatments are discussed.     

Adaptation and counteradaptation to complex optical distortion

The optical distortion caused by wearing a facemask in water magnifies the angular size of objects and reduces their optical distance. However, objects generallyappear to be further than their optical distance, with the result that points in the left part of the visual field are apparently displaced to the left, and those on the right to the right. Experiments on hand-eye coordination under water showed that adaptation to one aspect of the distortion produced some counteradaptation to complementary aspects: adaptation to distance produced increased lateral distortion, and adaptation to one side of the lateral distortion produced increased distortion on the opposite side. Nevertheless, “trading” was incomplete, and some overall adaptation of the visual metric occurred.     

Unconditional Self-Acceptance and Responses to Negative Feedback

Rational-emotive behavior therapy (REBT; Ellis, 1995) contends that esteeming oneself—favorably or unfavorably—is illogical (implying an objective basis for evaluating global worth) and counterproductive (making one prone to depression in the wake of setbacks, anxiety otherwise). A healthier outlook requires unconditional self-acceptance (USA). We evaluated predictions regarding USA in a nonclinical university student sample. Consistent with REBT, participants scoring high on a USA questionnaire, controlling for self-esteem level, reported being low in proneness to depression and in self-esteem lability. They also were more objective in evaluating their performance on a public speaking task and were less apt to denigrate people who provided negative evaluations of their speeches. Predictions regarding impression management, willingness to try another speech, and mood or state self-esteem reactivity to feedback were not supported. Discussion focused on implications for research on USA as well as applied implications for therapy or prevention programs.     

Adaptation to rearranged eye-foot coordination

The generality of adaptation following three types of movements during prism exposure was investigated. The three exposure conditions consisted of (1) walking with prisms, (2) viewing leg movements through prisms, and (3) viewing arm movements through prisms. The results showed that changes in eye-foot coordination and egocentric localization occur following both (1) and (2). Exposure Conditions 2 and 3 both produce changes in eye-hand coordination; however, eye-foot coordination was found unaltered following (3).     

Adaptation to delayed auditory feedback

Delayed auditory feedback disrupts the production of speech, causing an increase in speech duration as well as many articulatory errors. To determine whether prolonged exposure to delayed auditory feedback IDAFI leads to adaptive compensations in speech production, 10 subjects were exposed in separate experimental sessions to both incremental and constantdelay exposure conditions. Significant adaptation occurred for syntactically structured stimuli in the form of increased speaking rates. After DAF was removed, aftereffects were apparent for all stimulus types in terms of increased speech rates. A carry-over effect from the first to the second experimental session was evident as long as 29 days after the first session. The use of strategies to overcome DAF and the differences between adaptation to DAF and adaptation to visual rearrangement are discussed.     

First-Trial Adaptation to Prism Exposure

Terminal target-pointing error on the 1st trial of exposure to optical displacement is usually less than that expected from the optical displacement magnitude. Such 1st trial adaptation was confirmed in 2 experiments (N = 48 students in each) comparing pointing toward optically displaced targets and toward equivalent physically displaced targets (no optical displacement), with visual feedback delayed until movement completion. First-trial performance could not be explained by ordinary target undershoot, online correction, or reverse optic flow information about true target position and was unrelated to realignment aftereffects. Such adaptation might be an artifact of the asymmetry of the structured visual field produced by optical displacement, which induces a felt head rotation opposite to the direction of the displacement, thereby reducing the effective optical displacement.     

Adaptation to time-varying signals and control-theory models of tracking-behaviour

Summary Control-theory models of tracking behaviour imply continuous negative feedback as opposed to discrete control, and they assume the existence of a quadratic error criterion. The experimental induction of an asymmetric error criterion gives rise to a nonlinear control strategy which is used here to investigate the process of adaptation of tracking strategy to disturbances with varying statistical parameters. Results show that tracking behaviour adapts to time-varying signals, but this adaptation is not based on an estimate of the statistical parameters of the disturbance, as is assumed by an optimal-control model of tracking behaviour. It is suggested that continuous tracking behaviour is a special case induced by specific experimental conditions. In general, a view of tracking behaviour as a sequence of discrete actions seems more appropriate.This work was supported by Deutsche Forschungsgemeinschaft. Elke Melchior participated in this research     

HIV Locus of Control and Adaptation to Seropositivity1

The role of HIV locus of control in adaptation to HIV disease was evaluated in a sample of 588 military medical beneficiaries with predominantly asymptomatic, early stage HIV infection. Cluster analysis yielded 4 configurations of HIV locus of control, with high levels of depression related to a cluster where internal and powerful others control were highly endorsed. External attributions of control generally appeared more adaptive. Results are discussed in relation to Rotter's social learning theory and its implications for adaptive aspects of locus of control.