The horizontal-vertical illusion and knowledge of results

The Horizontal-Vertical (HV) Illusion was examined in two studies in which subjects adjusted the vertical line in L-shaped and inverted-T figures or produced lines in the vertical and horizontal planes. On the adjustment tasks, vertical lines were made significantly shorter than horizontal comparison lines, especially for the inverted-T figure. On the production tasks, lines drawn in the vertical plane were significantly shorter than lines drawn in the horizontal plane. The adjusted and created lines of subjects receiving intertrial feedback on illusion magnitude were significantly more accurate and less variable than the estimations of control subjects. Performance on either task or figure type did not differ as a function of sex of subject. The present results show that the HV illusion exists in the absence of line bisection or a comparison line and results from the overestimation of vertical lines. These findings further clarify the relative contributions of the structural and strategy mechanisms in the formation of the Horizontal-Vertical Illusion.     

Observational learning: effects of bandwidth knowledge of results

The authors investigated whether bandwidth knowledge of results (KR) during observation of a model's performance enhances motor skill learning. Following a pretest, 2 groups of participants (N = 28) observed a model practicing a timing task. The bandwidth group received KR about the model's performance only when his performance fell outside the criteria for a correct response. The yoked group received KR on the same trials as the bandwidth group did but were not told that the KR was only about incorrect performances. In that way, the authors avoided a confound between bandwidth and relative frequency effects on performance and learning. Following the observation phase, both groups of participants performed 10-min and 24-hr retention tests. Bandwidth KR enabled that group to reduce its performance variability and, to a lesser extent, to enhance its performance accuracy. The authors discuss the results with respect to the powerful effect of qualitative KR through observation.     

Effect of bandwidth knowledge of results on movement consistency

The effect of "bandwidth" knowledge of results (KR), given only if the subject's response is outside of a certain movement-time bandwidth, on learning and performance of a rapid elbow-flexion movement was examined. Subjects were randomly assigned to one of three feedback groups, a 5% bandwidth group (BW5), a 10% bandwidth group (BW10), or a control group (KR), who received knowledge of results on every trial. Subjects moved a light, horizontal, aluminum lever through 60 degrees in 200 msec., for 100 acquisition trials with KR given depending on group and 25 transfer trials without KR (transfer phase). Although the subjects in the BW10 group received knowledge of results fewer times during acquisition, they showed less within-subject variability than the BW5 and KR groups on the transfer test which suggests that giving KR about a relatively large bandwidth enhances movement consistency.     

Learning effects of knowledge of results upon time estimation

College students of both sexes served as their own controls to test three hypotheses in each of two separate experiments designed to assess the learning effects of knowledge of results upon time estimation. The results indicated that (1) knowledge of results in the form of feedback to the nearest hundredth of a second significantly increased the mean accuracy of time estimations obtained by the method of production, (2) that knowledge of results significantly decreased the variance of the time estimations, and (3) that sex difference as a main effect was not significant in either experiment. A major conclusion of the present study was that variance represents an authentic and independent measure of learning.     

Further learning effects of knowledge of results upon time estimation

College students of both sexes served as their own controls to test four hypotheses in each of three experiments designed to assess effects of knowledge of results (KR) as verbal information correct to the nearest .01 sec. on time estimations. Analysis indicated that (1) KR significantly increased the mean accuracy of time estimations obtained by the methods of production and estimation but not by the method of reproduction, (2) that KR significantly decreased the variance of the time estimations in all three experiments, (3) that in all three experiments after KR underestimators significantly increased their mean time estimates whereas overestimators significantly decreased their mean time estimations, and (4) that no significant sex differences were present. Notions of excitation and inhibition as intervening variables and of the Pavlovian first- and second-signalling systems were employed in tentative explanations.     

Synchronization and knowledge of results in a ventilatory motor task

The ability of healthy subjects to adopt a given value of inspiratory duration (TI) was examined in two different conditions: a knowledge condition in which subjects were informed of their performance on TI and synchronization of subjects' breathing rate to a periodic visual signal. The target value of TI was computed individually, by the same formula for all subjects in both procedures. 40 subjects were tested in a double-transfer design; each subject participated in two sessions 24 hr. apart. In addition to previous results showing better retention of the ventilatory task in subjects following the knowledge procedure after 24 hr., this study also shows better performance in this condition. No transfer could be evidenced, suggesting low similarity between the two tasks in spite of the fact that the resulting breathing patterns were nearly identical. The influence of the magnitude of the target on performance was also investigated.     

Knowledge of results for motor learning: relationship between error estimation and knowledge of results frequency

The authors of the present study investigated the apparent contradiction between early and more recent views of knowledge of results (KR), the idea that how one is engaged before receiving KR may not be independent of how one uses that KR. In a 2 ×: 2 factorial design, participants (N = 64) practiced a simple force-production task and (a) were required, or not required, to estimate error about their previous response and (b) were provided KR either after every response (100%) or after every 5th response (20%) during acquisition. A no-KR retention test revealed an interaction between acquisition error estimation and KR frequencies. The group that received 100% KR and was required to error estimate during acquisition performed the best during retention. The 2 groups that received 20% KR performed less well. Finally, the group that received 100% KR and was not required to error estimate during acquisition performed the poorest during retention. One general interpretation of that pattern of results is that motor learning is an increasing function of the degree to which participants use KR to test response hypotheses (J. A. Adams, 1971; R. A. Schmidt, 1975). Practicing simple responses coupled with error estimation may embody response hypotheses that can be tested with KR, thus benefiting motor learning most under a 100% KR condition. Practicing simple responses without error estimation is less likely to embody response hypothesis, however, which may increase the probability that participants will use KR to guide upcoming responses, thus attenuating motor learning under a 100% KR condition. The authors conclude, therefore, that how one is engaged before receiving KR may not be independent of how one uses KR.     

The role of knowledge of results frequency in learning through observation

The authors examined whether reduced knowledge of results (KR) frequency during observation of a model's performance enhances learning. As they viewed a timing task, observers (n = 54) received KR about the model's performance on each trial (100% KR) or on 1 out of 3 trials (33% KR). Controls (n = 18) received only physical practice; they did not take part in the observation session. The authors also wanted to dissociate the guidance effect of KR during physical practice from the guidance role played by the representation acquired during observation. Therefore, following the observation phase, participants physically performed the task with either the same or a different KR frequency than that experienced during observation. The effects of observation and physical practice on learning were assessed in delayed retention tests. The beneficial effect of reduced KR frequency during observation continued for the following physical practice phases. Possible explanations as to why KR influences observational learning are discussed.     

The influence of sleep deprivation and knowledge of results on perceptual encoding

This study investigates the way sleep deprivation effects on perceptual processes are modulated by knowledge of results (KR). In a choice-reaction task, signal quality was manipulated, combined with and without KR and under increasing levels of lack of sleep. It was found that the decrease of performance due to sleep deprivation was larger when stimuli were degraded. KR counteracted the effect of sleep deprivation; however, KR improved performance irrespective of signal quality. Hence, sleep deprivation seems to have a twofold effect on performance; one effect on perceptual processing, which is insensitive to KR, and another effect on some different processing stage, which is sensitive to KR. The results were interpreted in terms of a model of human performance (Sanders 1983) in which a distinction is made between two energetical mechanisms, ‘arousal’ and ‘activation’, subserving perceptual and motor stages of information processing, respectively. Thus, KR appears to compensate for the deficiency of one type of energetical mechanism, caused by sleep deprivation. Yet, this compensation does not appear to be the result of increased arousal, because, irrespective of KR, the performance decrement caused by signal degradation was more pronounced with lack of sleep.     

Learning a pressure under conditions of immediate and delayed knowledge of results

The results of a series of experiments on learning to reproduce a precise pressure are described and discussed in relation to a tentative hypothesis about the importance of timing of feedback signals. The evidence supports the contention that a careful analysis of the perceptual aspects of performance is necessary to account for the acquisition and retention of a precise motor response. Whilst the original hypothesis is sustained, other factors leading to the same result are clearly important. New evidence is produced which strongly suggests that cues presented simultaneously in two modalities interact. A possible distinction between sensory feedback which is used to control a response and feedback which cannot so be used, and the relation of this distinction to the learning of the response is also discussed.     

Erroneous knowledge of results affects decision and memory processes on timing tasks

On mental timing tasks, erroneous knowledge of results (KR) leads to incorrect performance accompanied by the subjective judgment of accurate performance. Using the start-stop technique (an analogue of the peak interval procedure) with both reproduction and production timing tasks, the authors analyze what processes erroneous KR alters. KR provides guidance (performance error information) that lowers decision thresholds. Erroneous KR also provides targeting information that alters response durations proportionately to the magnitude of the feedback error. On the production task, this shift results from changes in the reference memory, whereas on the reproduction task this shift results from changes in the decision threshold for responding. The idea that erroneous KR can alter different cognitive processes on related tasks is supported by the authors' demonstration that the learned strategies can transfer from the reproduction task to the production task but not visa versa. Thus effects of KR are both task and context dependent.