Explore the vast range of titles available.

Humans achieve skilled actions by continuously correcting for motor errors or perceptual misjudgments, a process called sensorimotor adaptation . This can occur with the actor both detecting (explicitly) and not detecting the error (implicitly). We investigated how the magnitude of a perturbation and the corresponding error signal each contribute to the detection of a size perturbation during interaction with real-world objects. Participants grasped cuboids of different lengths in a mirror-setup allowing us to present different sizes for seen and felt cuboids, respectively. Visuo-haptic size mismatches (perturbations) were introduced either abruptly or followed a sinusoidal schedule. These schedules dissociated the error signal from the visuo-haptic mismatch: Participants could fully adapt their grip and reduce the error when a perturbation was introduced abruptly and then stayed the same, but not with a constantly changing sinusoidal perturbation. We compared participants’ performance in a two-alternative forced choice (2AFC) task where participants judged these mismatches, and modelled error-correction in grasping movements by looking at changes in maximum grip apertures, measured using motion tracking. We found similar mismatch-detection performance with sinusoidal perturbation schedules and the first trial after an abrupt change, but decreasing performance over further trials for the latter. This is consistent with the idea that reduced error signals following adaptation make it harder to detect perturbations. Error-correction parameters indicated stronger error-correction in abruptly introduced perturbations. However, we saw no correlation between error-correction and overall mismatch-detection performance. This emphasizes the distinct contributions of the perturbation magnitude and the error signal in helping participants detect sensory perturbations.

Mismatch negativity (MMN) essentially reflects auditory change detection. Although auditory change detection can potentially be assessed through behavioral auditory testing methods, the increased reliability of objective methods, such as MMN, makes them more valuable. The aim of this study was to detect and compare the intensity just noticeable difference using the MMN and a behavioral method. The level at which the intensity difference between the frequent stimulus and the infrequent stimulus was the lowest and the MMN wave elicited was accepted as the MMN threshold. A total of 60 subjects, 30 females (mean age 21.70, SD = 1.91 years) and 30 males (mean age 22.77, SD = 3.01), aged 20–30 years, were included in the study. In the whole sample, a significant difference was found between MMN thresholds obtained from the right ear side and MMN thresholds obtained from the left ear side, regardless of sex (p < 0:05). In the comparison of the values obtained using the behavioral method and MMN, no significant difference was found for either the right or the left side in both sexes (p > 0:05). The results showed that the values determined by the behavioral method and MMN on both the right and left ear sides were similar in both sexes.

Just-Noticeable Difference (JND) in an image/video refers to the maximum difference that the human visual system cannot perceive, which has been widely applied in perception-guided image/video compression. In this work, we propose a Binary Decision-based Video-Wise Just-Noticeable Difference Prediction Method (BD-VW-JND-PM) with deep learning. Firstly, we model the VW-JND prediction problem as a binary decision process to reduce the inferring complexity. Then, we propose a Perceptually Lossy/Lossless Predictor for Compressed Video (PLLP-CV) to identify whether the distortion can be perceived or not. In the PLLP-CV, a Spatial–Temporal Network-based Perceptually Lossy/Lossless predictor (ST-Network-PLLP) is proposed for key frames by learning the spatial and temporal distortion features, and a threshold-based integration strategy is proposed to obtain the final results. Experimental results evaluated on the VideoSet database show that the mean prediction accuracy of PLLP-CV is about 95.6%, and the mean JND prediction error is 1.46 in QP and 0.74 in Peak-to-Noise Ratio (PSNR), which achieve 15% and 14.9% improvements, respectively.

The manual estimation task requires that participants separate the distance between their thumb and forefinger until they perceive it to match the size of a target object. Ganel and colleagues (Curr Biol 18:R599–R601, 2008a ) demonstrated that manual estimations yield just-noticeable-difference (JND) scores that linearly increased with increasing target object size; that is, responses adhered to Weber’s law and thus evince response mediation via relative and perception-based visual information. In turn, more recent work has reported that the size of a target object influences whether JNDs provide a reliable metric for evaluating the nature of the visual information supporting manual estimations. In particular, Bruno et al. (Neuropsychologia 91:327–334, 2016 ) reported that JNDs for ‘large’ target objects (i.e., 80 and 120 mm) violate Weber’s law due to biomechanical limits in aperture opening. It is, however, important to recognize that the absolute size of the ‘large’ target objects employed by Bruno et al. may have exceeded some participants’ functional aperture separation and resulted in a biomechanical strategy serving as the only viable response mode. Hence, the present investigation employed a manual estimation task wherein target object sizes were proportionately matched to decile increments (i.e., 10, 20, …, 70 and 80%) of individual participants’ maximal aperture separation. Results showed that JNDs increased linearly with increasing target object size. Accordingly, we propose that manual estimations of target objects within a functionally ‘graspable’ range adhere to Weber’s law and are mediated via relative and perception-based visual information.

This paper provides a comprehensive review of the Type B effect (TBE), a phenomenon reflected in the observation that discrimination sensitivity varies with the order of stimuli in comparative judgment tasks, such as the two-alternative forced-choice (2AFC) paradigm. Specifically, when the difference threshold is lower (higher) with the constant standard preceding rather than following the variable comparison, one speaks of a negative (positive) TBE. Importantly, prominent psychophysical difference models such as signal detection theory (Green & Swets, 1966) cannot easily account for the TBE, and are hence challenged by it. The present meta-analysis provides substantial evidence for the TBE across various stimulus attributes, suggesting that the TBE is a general feature of discrimination experiments when standard and comparison are presented successively. Thus, inconsistent with psychophysical difference models, subjective differences between stimuli are not merely a function of their physical differences but rather also depend on their temporal order. From the literature, we identify four classes of potential candidate theories explaining the origin of the TBE, namely (1) differential weighting of the stimulus magnitudes at the two positions (e.g., Hellström, Psychological Research, 39, 345–388 1977), (2) internal reference formation (e.g., Dyjas, Bausenhart, & Ulrich, Attention, Perception, & Psychophysics, 74, 1819–1841 2012), (3) Bayesian updating (e.g., de Jong, Akyürek, & van Rijn, Psychonomic Bulletin and Review, 28, 1183–1190 2021), and (4) biased threshold estimation (García-Pérez & Alcalá-Quintana, Attention, Perception & Psychophysics, 72, 1155–1178 2010). As these models, to some extent, make differential predictions about the direction of the TBE, investigating the respective boundary conditions of positive and negative TBEs might be a valuable perspective for diagnostic future research.

Video coding removes spatial, temporal, and statistic redundancies. After H.265, to further improve the coding efficiency, many efforts have been dedicated to removing the perceptual redundancy by using human perception-based methods. Just noticeable difference (JND) gives a good approximation for the human visual system and provides a valuable solution to remove the perceptual redundancy for perceptual video coding (PVC). However, there are still problems in the PVC architecture and the JND profile. One is although the whole discrete cosine transform (DCT) block are suppressed, there are still many transform coefficients below the suppression levels which are not adequately suppressed. Another problem is, to the best of our knowledge, most JND profiles are measured by image-based test methods and past display equipment. However, compared to images, videos exhibits temporal characteristics, and the current trend of the display equipment is towards full high definition. To solve these problems, we first propose a high efficiency video coding (HEVC)-compliant PVC architecture, where the coefficients in a DCT block can be adequately suppressed in a whole block manner. Second, we propose a video-based test method to model the temporal masking (TM) effect, called TM-JND. Experimental results show that the proposed TM-JND model can more accurately estimate the JND values for today’s display equipment and videos, avoiding the overestimate of the JND values like other existing models. The proposed PVC architecture achieves a significant bitrate reduction with a negligible subjective quality loss, compared with the HEVC test model HM 16.9.

The visual expertise of adult humans is jointly determined by evolution, visual development, and visual perceptual learning. Perceptual learning refers to performance improvements in perceptual tasks after practice or training in the task. It occurs in almost all visual tasks, ranging from simple feature detection to complex scene analysis. In this Review, we focus on key behavioral aspects of visual perceptual learning. We begin by describing visual perceptual learning tasks and manipulations that influence the magnitude of learning, and then discuss specificity of learning. Next, we present theories and computational models of learning and specificity. We then review applications of visual perceptual learning in visual rehabilitation. Finally, we summarize the general principles of visual perceptual learning, discuss the tension between plasticity and stability, and conclude with new research directions.

Intracortical microstimulation (ICMS) is a powerful tool to investigate the functional role of neural circuits and may provide a means to restore sensation for patients for whom peripheral stimulation is not an option. In a series of psychophysical experiments with nonhuman primates, we investigate how stimulation parameters affect behavioral sensitivity to ICMS. Specifically, we deliver ICMS to primary somatosensory cortex through chronically implanted electrode arrays across a wide range of stimulation regimes. First, we investigate how the detectability of ICMS depends on stimulation parameters, including pulse width, frequency, amplitude, and pulse train duration. Then, we characterize the degree to which ICMS pulse trains that differ in amplitude lead to discriminable percepts across the range of perceptible and safe amplitudes. We also investigate how discriminability of pulse amplitude is modulated by other stimulation parameters—namely, frequency and duration. Perceptual judgments obtained across these various conditions will inform the design of stimulation regimes for neuroscience and neuroengineering applications.

The just noticeable difference (JND) model reflects the visibility limitations of the human visual system (HVS), which plays an important role in perceptual image/video processing and is commonly applied to perceptual redundancy removal. However, existing JND models are usually constructed by treating the color components of three channels equally, and their estimation of the masking effect is inadequate. In this paper, we introduce visual saliency and color sensitivity modulation to improve the JND model. Firstly, we comprehensively combined contrast masking, pattern masking, and edge protection to estimate the masking effect. Then, the visual saliency of HVS was taken into account to adaptively modulate the masking effect. Finally, we built color sensitivity modulation according to the perceptual sensitivities of HVS, to adjust the sub-JND thresholds of Y, Cb, and Cr components. Thus, the color-sensitivity-based JND model (CSJND) was constructed. Extensive experiments and subjective tests were conducted to verify the effectiveness of the CSJND model. We found that consistency between the CSJND model and HVS was better than existing state-of-the-art JND models.

To investigate the effect of prolonged time before analysis and mechanical manipulation on pre-analytical stability of biomarkers and the validity of blood gas analysis results. We collected blood samples from 240 ICU patients from May 18, 2022 to March 31, 2023. Samples were analyzed immediately per standard operating procedure, then the syringes were kept at room temperature for 60 min, subjected to standardized mechanical forces (repeated drops) and analyzed again. Thirteen typical blood gas analytes were measured. Bland-Altman plots were prepared to assess differences between initial and delayed analyses. Differences were compared against official accuracy limits specified in German quality assurance guidelines (Rili-BAEK). For hemoglobin, creatinine, glucose, and electrolytes (calcium, sodium, chloride, bicarbonate), agreement between immediate and post-delay analyses remained within the official acceptable ranges. For pH and potassium, deviations exceeded the Rili-BAEK accuracy limits but remained clinically acceptable. Only oxygen partial pressure and lactate levels changed so markedly that they would no longer be reliable for clinical interpretation. Even after a 60-min delay and excessive mechanical stress, selected blood gas analytes such as hemoglobin, glucose, and electrolytes can be considered valid. Potassium and carbon dioxide partial pressure were altered but might be suitable for approximation purposes. Findings for oxygen partial pressure and lactate were generally invalid. In the future, these findings can aid in reducing unnecessary blood sampling. These findings may guide clinicians in deciding whether repeat sampling is necessary, potentially reducing unnecessary blood draws, while reinforcing that critical parameter (pO₂, pCO₂, pH) still require prompt analysis.