How do Distributions of Item Sizes Affect the Precision and Bias in RepresentingSummary Statistics?

Many studies have shown that observers can accuratelyperceive and evaluate the statistical summary of presentedobjects’ attribute values, such as the average, withoutattending to each object. However, it remains controversialhow the visual system integrates the attribute values (e.g.,information on size) of multiple items and computes theaverage value. In this study, we tested how distributions ofitem sizes affect the precision and bias in judging averagevalues. We predicted that if observers utilize all of theavailable size information equally, the distribution wouldhave no effect, and vice versa. Our results showed that, withnovice observers, judgement precision differed among sizedistributions and that the observers overestimated the size ofthe average value compared to the actual size under allconditions. These results imply that observations of someitems in a set could be weighted more easily than others, withthe possibility that this process is easier for larger items thansmaller ones. However, this was not the case for experiencedobservers, who showed no effects of distribution type onaverage assessment performance. Our findings imply that theprocess of representing the average value may not beexplained by a single definitive mechanism and, is rathermediated by a mixture of multiple cognitive processes

Summary statistics extracted in tactile feature

Many studies have shown that people may have the ability to extract summary statistics over objects/events in a set. Most of the investigations have mainly used simultaneous presented visual features. This experiment tested whether and how people could represent the average value over tactile stimuli presented in a temporal sequence. A voice-coil type vibrator was used to present the stimuli. In the averaging task, a sequence of stimuli was presented first, followed by a single stimulus. The sequence was composed of 4, 6, or 8 vibro-tactile stimuli. Participants judged whether the vibration intensity of the second stimulus was stronger or weaker than the estimated average value of the first sequence. The result demonstrated that 1) people can extract the average tactile stimuli, and 2) averaged intensity tend to be overestimated than the single stimuli. We will discuss characteristics of the summary statistical representation in the tactile modality

Can we match the variance across different visual features?

“Sensibility to variation” is considered to be a significant cognitive mechanism for adaptive decision making and action. It has been demonstrated that humans as well as animals have the ability in many perceptual properties. Here we tested whether people can compare and match the variance across perceptual domain. We examined subjective equal levels of variance across different perceptual properties, size and orientation, using the method of adjustment. The size- and the orientation-adjustment tasks were conducted in a between- subjects design. The point of subjective equalities (PSE) of the three target set variance levels were obtained. The results indicate that observers could adjust the size variance according to the direction variance in the size-adjustment task and do the reverse in the direction-adjustment task, and that the relation between the variance magnitudes of the two domains is linearly related. The result implies that people can sense the magnitude of variability of set of items and match the magnitude across perceptual domains

Friction Coefficient of Well-Defined Hydrogel Networks

The friction coefficient between Tetronic gel and water is measured as a function of the polymer concentration of the gel and the temperature by a simply designed apparatus. Tetronic gel was prepared by cross-linking Tetronic macromonomers through activated ester chemistry. The gel is expected to have homogeneous network structure. The polymer concentration <i>C</i>_p dependence of the friction coefficient <i>f</i> is well expressed by a power law relationship <i>f</i> ∼ <i>C</i>_p^ν with the exponent of ν = 1.5, which is in a good agreement with the prediction of the scaling theory. The friction coefficient normalized by viscosity of water, <i>f</i>(<i>T</i>)/η­(<i>T</i>), increases with temperature. When the network is homogeneous, the mesh size is given by the average distance between the nearest polymer–polymer contacts. Therefore, the increase in the ratio <i>f</i>(<i>T</i>)/η­(<i>T</i>) with temperature attributed to the decrease in the average mesh size of the network due to the dehydration of the chains at higher temperature. The friction coefficient for randomly cross-linked Tetronic gel prepared by enzyme-mediated cross-linking reaction of tyrosin-modified Tetronic is compared with that of the homogeneous Tetronic gel. The friction coefficient for the randomly cross-linked gel is about an order of magnitude smaller than that for homogeneous gel. It suggests that the friction coefficient is mainly governed by the spatial inhomogeneity frozen in the gel rather than the average cross-linking density of the gel