On the Identifiability of 3- and 4-Parameter Item Response Theory Models From the Perspective of Knowledge Space Theory.

The present work aims at showing that the identification problems (here meant as both issues of empirical indistinguishability and unidentifiability) of some item response theory models are related to the notion of identifiability in knowledge space theory. Specifically, that the identification problems of the 3- and 4-parameter models are related to the more general issues of forward- and backward-gradedness in all items of the power set, which is the knowledge structure associated with IRT models under the assumption of local independence. As a consequence, the identifiability problem of a 4-parameter model is split into two parts: a first one, which is the result of a trade-off between the left-side added parameters and the remainder of the Item Response Function, e.g., a 2-parameter model, and a second one, which is the already well-known identifiability issue of the 2-parameter model itself. Application of the results to the logistic case appears to provide both a confirmation and a generalization of the current findings in the literature for both fixed- and random-effects IRT logistic models.

Evidence of weight-based representations of gravitational motion.

A hypothesis gaining increasing popularity is that laypeople's representations of physical phenomena might be driven by internalized physical laws. In three experiments, we tested if such hypothesis holds true for the representation of gravitational motion. Participants were presented with realistic, real-scale virtual spheres falling vertically downward from about 2 m high. The spheres appeared to be made of either polystyrene or wood. In Experiment 1, participants adjusted the falling motion pattern until it appeared to be natural. In Experiment 2, they compared the perceived naturalness of vertical free falls in a vacuum with the perceived naturalness of more realistic falls characterized by the presence of air drag. In Experiment 3, they estimated the position of the sphere after a variable interval of time from the beginning of the fall. Inconsistently with predictions from physics, results showed that representations of gravitational motion were strongly affected by the implied masses of the falling objects and did not account for air drag. This provides support for the hypothesis of weight-based heuristic representations of gravitational motion against the hypothesis of the internalization of physical laws. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Seeking certainty about Intolerance of Uncertainty: Addressing old and new issues through the Intolerance of Uncertainty Scale-Revised.

Intolerance of Uncertainty is a trans-diagnostic process that spans a range of emotional disorders and it is usually measured through the Intolerance of Uncertainty Scale-12. The current study aims at investigating some issues in the assessment of Intolerance of Uncertainty (IU) through the Italian Intolerance of Uncertainty Scale-Revised, a measure adapted from the Intolerance of Uncertainty Scale-12 to assess IU across the lifespan. In particular we address the factor structure among a large community sample, measurement invariance across gender, age, and over time, together with reliability and validity of the overall scale and its subscales. The questionnaire was administered to community (N = 761; mean age = 35.86 ± 14.01 years) and undergraduate (N = 163; mean age = 21.16 ± 2.64 years) participants, together with other self-report measures assessing constructs theoretically related to IU. The application of a bifactor model shows that the Italian Intolerance of Uncertainty Scale-Revised possesses a robust general factor, thus supporting the use of the unit-weighted total score of the questionnaire as a measure of the construct. Furthermore, measurement invariance across gender, age, and over time is supported. Finally, the Italian Intolerance of Uncertainty Scale-Revised appears to possess adequate reliability and validity. These findings support the unidimensionality of the measure, a conceptually reasonable result in line with the trans-diagnostic nature of Intolerance of Uncertainty. In addition, this study and comparison with published factor structures of the Intolerance of Uncertainty Scale-12 and of the Intolerance of Uncertainty Scale-Revised identify some issues for the internal structure of the measure. In particular, concern is expressed for the Prospective IU subscale. In light of the promising psychometric properties, the use of the Italian Intolerance of Uncertainty Scale-Revised as a univocal measure is encouraged in both research and clinical practice.

Intuitive physics of gravitational motion as shown by perceptual judgment and prediction-motion tasks.

In Experiment 1, we explored participants' perceptual knowledge of vertical fall by presenting them with virtually simulated polystyrene or wooden spheres falling to the ground from about two meters high. Participants rated the perceived naturalness of the motion. Besides the implied mass of the sphere, we manipulated the motion pattern (i.e., uniform acceleration vs. uniform velocity), and the magnitude of acceleration or velocity. Results show that relatively low values of acceleration or velocity were judged as natural for the polystyrene sphere, whereas relatively high values of acceleration or velocity were judged as natural for the wooden sphere. In Experiment 2, the same stimuli of Experiment 1 were used, but the sphere disappeared behind an invisible occluder at some point of its trajectory. Participants were asked to predict the time-to-contact (TTC) of the sphere with the ground by pressing a key at the exact time of impact of the lower edge of the sphere with the floor of the room. Results show that the estimated TTC for the simulated wooden sphere was slightly but consistently smaller than the estimated TTC for the simulated polystyrene sphere. The influence of the implied mass on participants' responses might be the manifestation of two processes, namely an explicit 'heavy-fast, light-slow' heuristic, and/or an implicit, automatic association between mass and falling speed.

On a Generalization of Local Independence in Item Response Theory Based on Knowledge Space Theory.

Knowledge space theory (KST) structures are introduced within item response theory (IRT) as a possible way to model local dependence between items. The aim of this paper is threefold: firstly, to generalize the usual characterization of local independence without introducing new parameters; secondly, to merge the information provided by the IRT and KST perspectives; and thirdly, to contribute to the literature that bridges continuous and discrete theories of assessment. In detail, connections are established between the KST simple learning model (SLM) and the IRT General Graded Response Model, and between the KST Basic Local Independence Model and IRT models in general. As a consequence, local independence is generalized to account for the existence of prerequisite relations between the items, IRT models become a subset of KST models, IRT likelihood functions can be generalized to broader families, and the issues of local dependence and dimensionality are partially disentangled. Models are discussed for both dichotomous and polytomous items and conclusions are drawn on their interpretation. Considerations on possible consequences in terms of model identifiability and estimation procedures are also provided.

Anodal and cathodal electrical stimulation over V5 improves motion perception by signal enhancement and noise reduction.

BACKGROUND: The effect that transcranial direct current stimulation (tDCS) has on discrimination of coherent motion (CM) signals in a field of randomly moving dots (noise) can be accounted for by both noise reduction and signal enhancement. OBJECTIVE: To distinguish between noise reduction and signal enhancement, we monitored the discrimination of the correct CM direction as a function of the coherence level (using the psychophysical method of constant stimuli). We then analyzed the threshold and slope parameters. METHOD: Thirty observers participated in the experiment; fifteen received cathodal stimulation, and fifteen received anodal stimulation, all over left V5. RESULTS: The results showed that, rather than having opposite effects on CM discriminability, the positive- and negative-polarity tDCS over V5 affected the two parameters differently. When compared to a sham stimulation, anodal tDCS reduced the threshold, thus indicating signal enhancement. On the other hand, cathodal tDCS reduced the steepness of the slope (with better performance at low levels of coherence) compared to the sham stimulation, thus indicating noise reduction. Moreover, the results showed that late perceptual learning improved the participants' performance at medium/high CM similar to what anodal tDCS did. CONCLUSION: These results suggest a dissociation between the neural mechanisms responsible for enhanced CM discriminability: reduction of noisy or uncorrelated motion by cathodal tDCS versus increased activation of weakly correlated motion signals by anodal tDCS or perceptual learning.

Predicting organic food consumption: A meta-analytic structural equation model based on the theory of planned behavior.

During the last decade, the purchase of organic food within a sustainable consumption context has gained momentum. Consequently, the amount of research in the field has increased, leading in some cases to discrepancies regarding both methods and results. The present review examines those works that applied the theory of planned behavior (TPB; Ajzen, 1991) as a theoretical framework in order to understand and predict consumers' motivation to buy organic food. A meta-analysis has been conducted to assess the strength of the relationships between attitude, subjective norms, perceived behavioral control, and intention, as well as between intention and behavior. Results confirm the major role played by individual attitude in shaping buying intention, followed by subjective norms and perceived behavioral control. Intention-behavior shows a large effect size, few studies however explicitly reported such an association. Furthermore, starting from a pooled correlation matrix, a meta-analytic structural equation model has been applied to jointly evaluate the strength of the relationships among the factors of the original model. Results suggest the robustness of the TPB model. In addition, mediation analysis indicates a potential direct effect from subjective norms to individual attitude in the present context. Finally, some issues regarding methodological aspects of the application of the TPB within the context of organic food are discussed for further research developments.

Explorative surgery for acute scrotal pain: The importance of patient age, side affected, time to surgery and surgeon.

INTRODUCTION AND OBJECTIVE: Testicular torsion must be diagnosed quickly and accurately. The delay of the diagnosis and the subsequent delay of surgery may lead to loss testicular viability and orchidectomy. Aim of our retrospective evaluation was to define which element should be considered as major support to the clinician in distinguishing spermatic cord torsion from the other diseases mimicking this clinical emergency requiring surgical exploration. MATERIAL AND METHODS: We retrospectively reviewed all clinical and instrumental data of emergency scrotal exploration performed for acute scrotal pain at two different Urological Department in a 10 year period. Results of surgical exploration represented the four diagnostic categories in which patients were divided for statistical evaluation. We evaluated the relationship between diagnosis performed by testicular surgical exploration and the all clinical data available including surgeon involved in the procedures. RESULTS: A total of 220 explorative scrotal surgery were considered. We divided the cases in 4 categories according to the diagnostic results of each surgical procedure. Of all, spermatic cord torsion was diagnosed in 45% (99/220). The total testis salvage rate was of 78.8%. The patients with a diagnosis of spermatic cord torsion were older than patients with appendix torsion (15 vs 11 years in mean). When the affected side was the left, the probability to have a diagnosis of spermatic cord torsion was higher than the right side [χ2 (2, N = 218) = 11.77, p < 0.01]. Time elapsing between onset of symptoms and testicular salvagewas significantly lower even than in case of appendix torsion/necrosis (p < .0001), and of others pathologies diagnosed (p = .0383). CONCLUSION: In case of spermatic cord torsion, in addition to the clinical data, patient age and left side affected may represent an independent diagnostic predicting factor. The time elapsing between onset of symptoms and explorative surgery remain the only still prognostic factor for testicular viability.

Modeling the Overalternating Bias with an Asymmetric Entropy Measure.

Psychological research has found that human perception of randomness is biased. In particular, people consistently show the overalternating bias: they rate binary sequences of symbols (such as Heads and Tails in coin flipping) with an excess of alternation as more random than prescribed by the normative criteria of Shannon's entropy. Within data mining for medical applications, Marcellin proposed an asymmetric measure of entropy that can be ideal to account for such bias and to quantify subjective randomness. We fitted Marcellin's entropy and Renyi's entropy (a generalized form of uncertainty measure comprising many different kinds of entropies) to experimental data found in the literature with the Differential Evolution algorithm. We observed a better fit for Marcellin's entropy compared to Renyi's entropy. The fitted asymmetric entropy measure also showed good predictive properties when applied to different datasets of randomness-related tasks. We concluded that Marcellin's entropy can be a parsimonious and effective measure of subjective randomness that can be useful in psychological research about randomness perception.

A derivation of the polytomous rasch model based on the most probable distribution method

Boltzmann’s most probable distribution method is applied to derive the Polytomous Rasch model as the distribution accounting for the maximum number of possible outcomes in a test while introducing latent traits, item characteristics, and thresholds as constraints to the system. Affinities and similarities of the present result with other derivations of the model are discussed in light of the conceptual frameworks of statistical physics and of the principle of maximum entropy (AU)

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An analysis of item response theory and Rasch models based on the most probable distribution method.

The most probable distribution method is applied to derive the logistic model as the distribution accounting for the maximum number of possible outcomes in a dichotomous test while introducing latent traits and item characteristics as constraints to the system. The item response theory logistic models, with a particular focus on the one-parameter logistic model, or Rasch model, and their properties and assumptions, are discussed for both infinite and finite populations.

A derivation of the Polytomous Rasch model based on the most probable distribution method.

Boltzmann's most probable distribution method is applied to derive the Polytomous Rasch model as the distribution accounting for the maximum number of possible outcomes in a test while introducing latent traits, item characteristics, and thresholds as constraints to the system. Affinities and similarities of the present result with other derivations of the model are discussed in light of the conceptual frameworks of statistical physics and of the principle of maximum entropy.

A variational approach to behavioral and neuroelectrical laws.

Variational methods play a fundamental and unifying role in several fields of physics, chemistry, engineering, economics, and biology, as they allow one to derive the behavior of a system as a consequence of an optimality principle. A possible application of these methods to a model of perception is given by considering a psychophysical law as the solution of an Euler-Lagrange equation. A general class of Lagrangians is identified by requiring the measurability of prothetic continua on interval scales. The associated Hamiltonian (the energy of the process) is tentatively connected with neurophysiological aspects. As an example of the suggested approach a particular choice of the Lagrangian, that is a sufficient condition to obtain classical psychophysical laws, while accounting for psychophysical adaptation and the stationarity of neuronal activity, is used to explore a possible relation between a behavioral law and a neuroelectrical ,response based on the Naka-Rushton model.

Trusting beliefs: a functional measurement study

Trust is a fundamental aspect of everyday life. Several authors define trust as the wish to depend on another entity and split the concept of trust into several interconnected components such as trusting beliefs (e.g., benevolence, competence, honesty, and predictability), trusting intentions, trusting behaviors, disposition to trust, and institution-based trust. According to McKnight, Cummings, and Chervany’s (1998) model, beliefs yield behavioral intentions, which in turn are manifested in behavior. In the present research, we applied functional measurement to explain trust-related judgments in terms of information integration among different beliefs. Our results suggest that averaging models could help to describe the observed judgments in terms of beliefs and to comprehend the role and relevance of each belief in a variety of social contexts(AU)

Is there a need for more than three models?

An important open issue in Functional Measurement is whether the three most important models of cognitive algebra are sufficient to describe the great majority of possible response behaviors. Generally speaking, the individual response R is a function of the subjective scale values sk and can be imagined as a continuous manifold. First and second order terms of a Taylor series are often used to locally approximate the shape of such a generic function. In this work we suggest that almost any response surface can be approximated by an additive, multiplicative or averaging model, considering that the Taylor expansion is cut at the second order at most. In particular, additive and multiplicative models appear to hold as global approximations, while the averaging model appears to be a connection of local approximations(AU)