Product Attributes, Evaluability, and Consumer Satisfaction

We studied the determinants of consumer satisfaction with mobile phones on the basis of their perceived product attribute performance, and the disconfirmation of product attribute expectations. Disconfirmation refers to the discrepancy between the prior expectation about the performance of a product’s attributes, and its perceives realizations after purchase. Evaluability theory assumes that the perceived attribute performance has a larger effect on consumer satisfaction for easy-to-evaluate than for difficult-to-evaluate attributes, after product acquisition. Furthermore, we used predictions of the asymmetric evaluations of gains (product performs better than expected) and losses (product performs worse than expected) from prospect theory, in combination with evaluability theory. We studied how evaluability influences the effects of the asymmetric evaluations of both positive and negative disconfirmation of product attribute expectations on consumer satisfaction. Our empirical study included 3099 participants of Amazon Mechanical Turk. We found that negative attribute disconfirmation had a larger effect on satisfaction than positive attribute disconfirmation, which is in line with loss aversion theory. Although the perceived product attribute performance positively influenced satisfaction, we found little support for the effects of perceived attribute performance being influenced by attribute evaluability. However, our findings indicated that negative attribute disconfirmation influenced satisfaction to a greater extent for relatively difficult-to-evaluate attributes than for relatively easy-to-evaluate attributes. We discuss both theoretical and managerial implications of our findings.

Does the data do the talking? Confirmation bias in the interpretation of data visualizations

When analyzing the results of an experiment, we often assume that the interpretation of the data is a straightforward act; however, experiments on reproducibility that have large numbers of scientists analyze the same dataset show that even subtle differences in workflows can lead to drastically different results. Beyond the use of different analysis methods, one potential reason for different conclusions from the same data is confirmation bias, a phenomenon well documented in psychology. We reasoned that confirmation bias might not only influence the choice of analysis methods and depth of analysis, but that it might even shape how different researchers interpret the same graphical representation of data. To test this notion, we designed a simple experiment, in which we contrast the prior expectation of participants’ for the relationship between two variables (income and happiness) with their interpretation of a corresponding data plot. We artificially engineered the data such that under superficial examination, it shows an overall negative correlation, while a closer look at distinct age groups (distinguished by color) reveals a within-group positive correlation. Prior to showing the plot, we had asked the participants whether they expected a positive or a negative relationship. We found that participants who expected a positive correlation were more than twice as likely to detect the positive within-age group correlation than those expecting a negative correlation. This simple experiment demonstrates the presence of confirmation bias in the interpretation of graphical data representations.

Prediction error boosts retention of novel words in adults but not in children

How do we update our linguistic knowledge? In seven experiments, we asked whether error-driven learning can explain under what circumstances adults and children are more likely to store and retain a new word meaning. Participants were exposed to novel object labels in the context of more or less constraining sentences or visual contexts. Both two-to-four-year-olds (Mage = 38 months) and adults were strongly affected by expectations based on sentence constraint when choosing the referent of a new label. In addition, adults formed stronger memory traces for novel words that violated a stronger prior expectation. However, preschoolers’ memory was unaffected by the strength of their prior expectations. We conclude that the encoding of new word-object associations in memory is affected by prediction error in adults, but not in preschoolers.

Extinction rates of non-avian dinosaur species are uncorrelated with the rate of evolution of phylogenetically informative characters

Determining the factors that shape temporal variation in species diversity is an ongoing challenge. One theory is that species exhibiting lower rates of phenotypic evolution should be more likely to go extinct as they are more susceptible to changing environmental conditions. However, little work has been done to assess whether this process shapes comparatively few lineages, or is a common mechanism shaping changes in species diversity. Here, I analyse the correlation between rates of morphological evolution and extinction at the species level using six published morphological matrices of non-avian dinosaurs. I find no correlation between the two rates at different taxonomic scales, suggesting that extinction in these groups is better described by other factors. As there is a strong prior expectation of correlated rates, I suggest that traditional morphological matrices are inappropriate for addressing this question and that the characters governing lineage persistence are independent of those with high phylogenetic signal. This may be comprehensively determined with continued development of phenomic matrices.

O6.5. JUMPING TO CONCLUSIONS ABOUT DECISION NOISE? A COMPUTATIONAL ANALYSIS OF THE RELATIONSHIP BETWEEN BELIEF UPDATING AND PSYCHOTIC SYMPTOMS IN A LARGE UK BIRTH COHORT

Background A number of studies show that people with psychotic disorders have abnormal belief-updating processes. In a commonly-used decision-making task, the beads task, participants infer which of two jars, each with a different ratio of coloured beads, a presented bead is drawn from, with an option to request further beads before reaching a decision. Previous studies suggest that people with psychotic symptoms request fewer beads (draws to decision; DTD) indicative of a ‘Jumping to conclusion’ (JTC) bias. In a modified version of this task, participants estimate the probability that beads have been drawn from one of the two jars on a sliding scale over a sequence of beads and are also told that the jar the beads are drawn from may switch. In this task, people with psychotic symptoms revise their estimations disproportionately in response to a change in colour of beads in a sequence (overadjustment bias). It is not clear what specific belief-updating processes drive these biases, how they arise, or if their association with psychotic symptoms is independent of confounding. We examined whether abnormal belief-updating processes are associated with psychotic experiences in a large, population-based sample, and whether they mediate the association between trauma and psychotic symptoms. Methods We used data from the Avon Longitudinal Study of Parents and Children birth cohort (n=2,879). Past-year frequent or distressing psychotic experiences (PEs) were assessed using the semi-structured PLIKS interview at age 24. Performance on the DTD and probability estimation tasks at age 24 were assessed using behavioural indices and computational modelling parameters (using ‘costed Bayesian’ and Hidden Markov Models respectively). Logistic regression was used to examine the association between belief-updating parameters (DTD task: cost of sampling, decision noise; Probability estimation task: adjustment rate, inference length, decision confidence, prior expectation of reversal, decision noise) and PEs. Estimates were adjusted for confounders (genetic risk for schizophrenia, socio-economic status, cognitive function). Mediation analysis tested abnormal belief-updating processes as a mediator between exposure to trauma (assessed ages 0–17 years) and age-24 PEs. Results In the DTD task, increased decision noise was associated with PEs (adjusted OR=1.89, 95% CI: 1.14, 3.13, p=0.014). There was little evidence of an association between the JTC bias and PEs (OR= 1.13; 95% CI: 0.45, 2.82). For the probability estimation task, there was an association between a higher prior expectation that the jars that will switch during the sequence (expectation of reversal) and PEs (adjusted OR = 2.28; 95% CI 1.39, 3.74, p=0.001). Our findings were minimally attenuated by confounding (<10%). Exposure to trauma was also associated with greater decision noise in the DTD task, but there was little evidence that this abnormal belief-updating parameter mediated the relationship between trauma and PEs (<1% mediated). Discussion Our results suggest that abnormal belief-updating processes (increased decision noise; greater prior expectation of reversal) are associated with PEs, and that this is not explained by general cognitive ability, shared genetic risk, or social background. Previous observations of association between the JTC bias and psychosis may be due to sub-optimal performance rather than a bias for making a decision on less evidence. The results also suggest that an increased expectation of change is associated with the early stages of psychosis symptom development. Our mediation result does not support the hypothesis that the belief-updating processes examined here lie on the causal pathway between trauma exposure and PEs.

First-order transition in a model of prestige bias

One of the major benefits of belonging to a prestigious group is that it affects the way you are viewed by others. Here I use a simple mathematical model to explore the implications of this ``prestige bias'' when candidates undergo repeated rounds of evaluation. In the model, candidates who are evaluated most highly are admitted to a ``prestige class'', and their membership biases future rounds of evaluation in their favor. I use the language of Bayesian inference to describe this bias, and show that it can lead to a runaway effect in which the weight given to the prior expectation associated with a candidate's class becomes stronger with each round. Most dramatically, the strength of the prestige bias after many rounds undergoes a first-order transition as a function of the precision of the examination on which the evaluation is based.

Criterion validity for step counting in four consumer-grade physical activity monitors among older adults with and without rollators

Background Few studies have investigated the measurement properties of consumer-grade physical activity monitors (PAMs) in older adults. Therefore, we investigated the criterion validity of consumer-grade PAMs in older adults and whether the measurement properties differed between older adults with and without rollators and whether worn on the hip or at the wrist. Methods Consumer-grade PAMs were eligible for inclusion in this study if they: 1) could be fastened at the hip as well as on the wrist, 2) were simple in function and design and thus easy to use for participants with minimal technical skills, 3) included step-counting as outcome measure and 4) were powered by a button cell battery. Participants performed self-paced walking for six minutes while two physiotherapists counted their steps with a click-counter. The average of the two counts was used as criterion. The participants wore 16 monitors, four located bilaterally on both hips and wrists. Our prior expectation was that all monitors would have at least moderate criterion validity for all participants, good criterion validity for participants walking without a rollator and poor criterion validity for participants walking with a rollator. Results Four physical activity monitors were included in this study; Misfit Shine, Nokia GO, Jawbone UP Move and Garmin Vivofit 3. A total of 103 older adults participated. Nokia GO was excluded from this study due to technical issues. Therefore, we present results on the frequency of data loss, ICC (1, 2) and percentage measurement error for Misfit Shine, Garmin Vivofit 3 and Jawbone UP Move located on four different positions. Conclusions The hip-worn PAMs did not differ significantly in terms of measurement error or criterion validity. Wrist-worn monitors cannot adequately measure number of steps in a population of older adults using rollators. The hip-worn PAMs were superior to wrist-worn PAMs among older adults with and without rollators.

Propagation, cocoon formation, and resultant destabilization of relativistic jets

ABSTRACT A cocoon is a by-product of a propagating jet that results from shock heating at the jet head. Herein, considering simultaneous cocoon formation, we study the stability of relativistic jets propagating through the uniform ambient medium. Using a simple analytic argument, we demonstrate that independent from the jet launching condition, the effective inertia of the jet is larger than that of the cocoon when the fully relativistic jet oscillates radially owing to the pressure mismatch between jet and cocoon. In such situations, it is expected that the onset condition for the oscillation-induced Rayleigh–Taylor instability is satisfied at the jet interface, resulting in the destabilization of the relativistic jet during its propagation. We have quantitatively verified and confirmed our prior expectation by performing relativistic hydrodynamic simulations in three dimensions. The possible occurrences of the Richtmyer–Meshkov instability, oscillation-induced centrifugal instability, and Kelvin–Helmholtz instability are also discussed.

Compton imaging with 99mTc for human imaging

We have been developing a medical imaging system using a Compton camera and demonstrated the imaging ability of Compton camera for 99mTc-DMSA accumulated in rat kidneys. In this study, we performed imaging experiments using a human body phantom to confirm its applicability to human imaging. Preliminary simulations were conducted using a digital phantom with varying activity ratios between the kidney and body trunk regions. Gamma rays (141 keV) were generated and detected by a Compton camera based on a silicon and cadmium telluride (Si/CdTe) detector. Compton images were reconstructed with the list mode median root prior expectation maximization method. The appropriate number of iterations of the condition was confirmed through simulations. The reconstructed Compton images revealed two bright points in the kidney regions. Furthermore, the numerical value calculated by integrating pixel values inside the region of interest correlated well with the activity of the kidney regions. Finally, experimental studies were conducted to ascertain whether the results of the simulation studies could be reproduced. The kidneys could be successfully visualised. In conclusion, considering that the conditions in this study agree with those of typical human bodies and imaginable experimental setup, the Si/CdTe Compton camera has a high probability of success in human imaging. In addition, our results indicate the capability of (semi-) quantitative analysis using Compton images.