A robust steganography method for HEVC based on secret sharing

This paper presents a robust steganography method for HEVC based on secret sharing. To prevent intra-frame distortion drift, three Classes of intra-frame prediction are defined. To improve the robustness of the secret message, the embedded message has been encoded into n sub-secrets by using (t, n)-threshold secret sharing. Then the encoded message is embedded into the multi-coefficients of the selected 4 × 4 luminance DST blocks which meet the Classes mentioned above. When the test video faced with different loss-rates, the survival rate of the proposed steganography method has increased by around 24.27%, 27.38%, 61.91% and 32.26% compared with Swati, Hayat, and Shahid (2014), respectively; the survival rate of the proposed steganography method has increased by around 28.74%, 34.60%, 56.05% and 41.40% compared with Liu, Liu, and Zhao (2017), respectively; when the loss-rate is less than 15%, the proposed steganography method can get 100% survival rate. And the experiments prove that the proposed method can achieve high performance than previously video steganography methods based on HEVC, especially for visual quality and robustness performance.     

Reinforcing saccadic amplitude variability

Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we reinforced the least frequent saccadic amplitudes to increase variability, and then reinforced the central part of the amplitude distributions to reduce variability. The target was placed at a constant distance from the fovea after the saccade to maintain the postsaccadic visual signal constant and an auditory reinforcement was delivered depending on saccadic amplitude. The second experiment tested the effects of the contingency. We reinforced high levels of variability in 4 participants, whereas 4 other participants were assigned to a yoked control group. On average, saccadic amplitude standard deviations were doubled while the medians remained mostly unchanged in the experimental participants in both experiments, and variability returned to baseline level when low variability was reinforced. In the control group no consistent changes in amplitude distributions were observed. These results, showing that variability can be reinforced, challenge the idea of a stochastic neural noise. We instead propose that selection processes constrain saccadic amplitude distributions.     

Item Parameter Drift in Context Questionnaires from International Large-Scale Assessments

The purpose of the current study was to examine the impact of item parameter drift (IPD) occurring in context questionnaires from an international large-scale assessment and determine the most appropriate way to address IPD. Focusing on the context of psychometric and educational research where scores from context questionnaires composed of polytomous items were employed for the classification of examinees, the current research investigated the impacts of IPD on the estimation of questionnaire scores and classification accuracy with five manipulated factors: the length of a questionnaire, the proportion of items exhibiting IPD, the direction and magnitude of IPD, and three decisions about IPD. The results indicated that the impact of IPD occurring in a short context questionnaire on the accuracy of score estimation and classification of examinees was substantial. The accuracy in classification considerably decreased especially at the lowest and highest categories of a trait. Unlike the recommendation from literature in educational testing, the current study demonstrated that keeping items exhibiting IPD and removing them only for transformation were appropriate when IPD occurred in relatively short context questionnaires. Using 2011 TIMSS data from Iran, an applied example demonstrated the application of provided guidance in making appropriate decisions about IPD.     

Evaluation of self-contained training procedures for the Time-Sample Behavioral Checklist

The comparative effectiveness of two time-limited modes of training observers to code the behavior of clients in residential treatment programs on the Time-Sample Behavioral Checklist (TSBC) was evaluated. The susceptibility of training procedures to consensual observer drift and the predictability of TSBC mastery from trainee characteristics were also examined. Two equated groups of undergraduate students (N=15 each) participated in full-time training on the TSBC and another instrument for 27 days, followed by criterion testingin vivo and on videotapes. One group was trained by experienced personnel using procedures known to be effective but potentially subject to consensual observer drift. The other group was trained using a previously untested set of written and videotape procedures that do not rely on experienced personnel. Comparative effectiveness and observer drift were evaluated by multivariate and univariate ANOVAs on mastery scores reflecting both pattern agreement and level differences between each trainee and criterion codings. The new, more efficient training procedures were found to be as effective as the original training procedures in the degree of mastery achieved by trainees. Original training procedures were found to be resistant to consensual observer drift, with such a phenomenon appearing in only 1 instance of 156 opportunities. The high degree of mastery achieved by trainees during the time-limited training period was comparable to that previously achieved with the original training procedures. No meaningful predictions of coding mastery were found, with only one trainee characteristic being significantly related to one of six mastery criteria. The results document procedures that are both efficient and resistant to invalidity for training observers in the use of multidimensional observational systems, as well as providing guidelines for the development of standardized procedures.This article is based on a thesis submitted to the Graduate College of the University of Illinois at Urbana-Champaign in partial fulfillment of the requirements for the Ph.D. degree in psychology by the first author and under direction of the second author. The third and fourth authors also participated as supervisors. Appreciation is extended to other members of the thesis committee, Fred Kanfer, Ross Parke, and Julian Rappaport, and to John Gottman and W. Robert Nay for their comments and recommendations. This study was partially supported by Public Health Service Grants MH-25464 and MH-14257 from the National Institute of Mental Health and by grants from the Joyce Foundation, the MacArthur Foundation, and the Illinois Department of Mental Health and Developmental Disabilities.     

The comparative effectiveness of two modes of observer training on the Staff-Resident Interaction Chronograph

The comparative effectiveness of two time-limited modes of training observers to code activity on the Staff-Resident Interaction Chronograph (SRIC) in residential treatment programs for mentally disabled adults was evaluated. The susceptibility of training procedures for consensual observer drift was also examined, as was the predictability of SRIC mastery from trainee characteristics. Two equated groups of undergraduate student trainees (N=15 each) participated in full-time training for 27 days, followed by two weeks of criterion testing in vivo and on videotapes. One group received training by experience personnel using procedures known to be effective (original method). The other group received training via a previously untested set of written and videotaped procedures that do not rely on experienced personnel (package method). Multivariate and univariate analyses of variance found both methods to be equally effective in the degree of mastery achieved by trainees, without evidence of observer drift. No meaningful predictions of coding mastery were found, but conceptual mastery was predictable from individual characteristics. Differences were obtained for both groups between in vivo versus videotaped criterion tests. The results document procedures that are both efficient and resistant to invalidity for complex observational methodology as well as feasible for standardizing assessment of staff functioning across residential settings.This article is based on a thesis submitted to the Graduate College of the University of Illinois at Urbana-Champaign in partial fulfillment of the requirements for the Ph.D. degree in psychology by the first author under direction of the second author. The third and fourth authors also participated as supervisors. Appreciation is extended to other members of the thesis committee, Fred Kanfer, W. Robert Nay, Julian Rappaport, and James Wardrop, for their comments and recommendations. This study was partially supported by Public Health Service Grants MH-25464 and MH-14257 from the National Institute of Mental Health, and by grants from The Joyce Foundation and the Illinois Department of Mental Health and Developmental Disabilities.     

First‐line therapy for post‐traumatic stress disorder: A systematic review of cognitive behavioural therapy and psychodynamic approaches

Background

Despite evidence supporting cognitive behavioural therapy (CBT)‐based interventions as the most effective approach for treating post‐traumatic stress disorder (PTSD) in randomised control trials, alternative treatment interventions are often used in clinical practice. Psychodynamic (PDT)‐based interventions are one example of such preferred approaches, this is despite comparatively limited available evidence supporting their effectiveness for treating PTSD.

Aims

Existing research exploring effective therapeutic interventions for PTSD includes trauma‐focused CBT involving exposure techniques. The present review sought to establish the treatment efficacy of CBT and PDT approaches and considers the potential impact of selecting PDT‐based techniques over CBT‐based techniques for the treatment of PTSD.

Results

The evidence reviewed provided examples supporting PDT‐based therapy as an effective treatment for PTSD, but confirmed CBT as more effective in the treatment of this particular disorder. Comparable dropout rates were reported for both treatment approaches, suggesting that relative dropout rate should not be a pivotal factor in the selection of a PDT approach over CBT for treatment of PTSD.

Conclusion/Implications

The need to routinely observe evidence‐based recommendations for effective treatment of PTSD is highlighted and factors undermining practitioner engagement with CBT‐based interventions for the treatment of PTSD are identified.     

Two hands are better than one: a new assessment method and a new interpretation of the non-visual illusion of self-touch

A simple experimental paradigm creates the powerful illusion that one is touching one’s own hand even when the two hands are separated by 15 cm. The participant uses her right hand to administer stimulation to a prosthetic hand while the Examiner provides identical stimulation to the participant’s receptive left hand. Change in felt position of the receptive hand toward the prosthetic hand has previously led to the interpretation that the participant experiences self-touch at the location of the prosthetic hand, and experiences a sense of ownership of the prosthetic hand. Our results argue against this interpretation. We assessed change in felt position of the participant’s receptive hand but we also assessed change in felt position of the participant’s administering hand. Change in felt position of the administering hand was significantly greater than change in felt position of the receptive hand. Implications for theories of ownership are discussed.     

Spatial limits on the nonvisual self-touch illusion and the visual rubber hand illusion: Subjective experience of the illusion and proprioceptive drift

The nonvisual self-touch rubber hand paradigm elicits the compelling illusion that one is touching one’s own hand even though the two hands are not in contact. In four experiments, we investigated spatial limits of distance (15 cm, 30 cm, 45 cm, 60 cm) and alignment (0°, 90° anti-clockwise) on the nonvisual self-touch illusion and the well-known visual rubber hand illusion. Common procedures (synchronous and asynchronous stimulation administered for 60 s with the prosthetic hand at body midline) and common assessment methods were used. Subjective experience of the illusion was assessed by agreement ratings for statements on a questionnaire and time of illusion onset. The nonvisual self-touch illusion was diminished though never abolished by distance and alignment manipulations, whereas the visual rubber hand illusion was more robust against these manipulations. We assessed proprioceptive drift, and implications of a double dissociation between subjective experience of the illusion and proprioceptive drift are discussed.     

The Effects of Video-Taped Feedback on Form,Accuracy, and Latency in an Open and Closed Environment

40 college women performed a modification of the classical fencing lunge against 2 laterally-arranged targets, under closed and open environmental conditions. Form (rating scale), accuracy (proximity to target center), and response latency were taken to measure the effects of video-taped feedback (VT). Administration of VT with specific instructions to direct S’s attention to parts of the display resulted in closer approximation of the externally-imposed form, higher accuracy, and shorter response latency. Performing the skill in the closed environmental condition resulted in less deviation from the imposed form, higher accuracy scores, and longer response latency. No significant correlations were found between imposed form and accuracy.     

Investigating Separate and Concurrent Approaches for Item Parameter Drift in 3PL Item Response Theory Equating

This study examines separate and concurrent approaches to combine the detection of item parameter drift (IPD) and the estimation of scale transformation coefficients in the context of the common item nonequivalent groups design with the three-parameter item response theory equating. The study uses real and synthetic data sets to compare the two approaches based on IPD flagging rates, type I error and power rates, and recovery of scale transformation coefficients. Results indicate that the two approaches render similar outcomes with stable anchor sets. However, they can produce dissimilar results with unstable anchor sets because of differences in the performance of their IPD components. Further, the findings of this study caution about working backward from equated cut scores to motivate the selection of an anchor set.