In 1993, Agostini and Proffitt showed that perceptual belongingness causes simultaneous lightness contrast to be seen in configurations in which the inducing elements are not adjacent to the target. The aim of the present research was to measure the strength of belongingness in determining the contrast phenomenon when the numbers of the inducing and induced elements and their relative positions are manipulated in Agostini-and-Proffitt-type configurations. In the first experiment, by using a forced choice paradigm, naïve observers indicated which gray disks (...) arranged to form the letter T in two rows appeared lighter/darker. In the second experiment, expert observers performed two nulling tasks: 1) the lightness of gray disk was adjusted until it was perceived equal to that of gray target aligned with white/black inducers; 2) the lightness of target organized with white/black inducers was adjusted to match the target organized with black/ white inducers. We found that also when there are few inducers, perceptual belongingness causes the contrast effect to propagate spatially on all the induced elements. Spatial position does not influence the induction effect. Low-level theories cannot account for these phenomena, but higher-level processes must be factored in to explain them. (shrink)

This article serves as a step-by-step guide of a new application of Q-methodology to investigate people’s preferences for multivariate stimuli. Q-methodology has been widely applied in fields such as sociology, education and political sciences but, despite its numerous advantages, it has not yet gained much attention from experimental psychologists. This may be due to the fact that psychologists examining preferences, often adopt stimuli resulting from a combination of characteristics from multiple variables, and in repeated measure designs. At present, Q methodology (...) has not been adapted to accommodate. We therefore developed a novel analysis procedure allowing Q-methodology to handle these conditions. We propose a protocol requiring five analyses of a decision process to estimate: the preference of stimuli, the dominance of variables, the individual differences, the interaction between individual differences and preference, and the interaction between individual differences and dominance. The guide comes with a script developed in R to run the five analyses; furthermore, we provide a case study with a detailed description of the procedure and corresponding results. This guide is particularly beneficial to conduct and analyze experiments in any research on people’s preferences, such as experimental aesthetics, prototype testing, visual perception, etc. (shrink)

The Mona Lisa is probably the most celebrated example of ambiguous expression in art. Soranzo and Newberry demonstrated that a similar ambiguity can be perceived also in La Bella Principessa, another portrait credited to Leonardo da Vinci by many. The paper aims to show that an ambiguous expression can be perceived in a further painting attributed to Leonardo: The Lady with Dishevelled Hair, or La Scapigliata. An experiment was conducted whereby participants rated on a 7-point Likert scale the perceived level (...) of contentment of La Scapigliata and that of a comparable painting created by Andrea di Cione, alias Il Verrocchio. The two artworks were presented in random order to two groups of participants. One group could see the artworks from Close whilst the other group from Far from a Close or Far condition. Results show that the change of distance affected the perceived level of contentment of Leonardo’s figure but not that of Verrocchio’s. Specifically, whilst both artworks received similar ratings of contentment from the close-up condition, La Scapigliata was perceived to be more content from afar. It is concluded that La Scapigliata exhibits an ambiguous expression, and that this ambiguity is similar to the one observed in the Mona Lisa and La Bella Principessa. This result can be only partially interpreted within the spatial frequency hypothesis advanced by Livingstone and shows that a phenomenological account of Leonardo’s work might be more suited to capture the full extent of the phenomenon. Specifically, it is suggested that the principles of perceptual belongingness may need to be considered to fully capture the extent of the ambiguity depicted by Leonardo. (shrink)

The problem is posed of the prescription of the so-called Boltzmann–Grad limit operator ) for the N-body system of smooth hard-spheres which undergo unary, binary as well as multiple elastic instantaneous collisions. It is proved, that, despite the non-commutative property of the operator \, the Boltzmann equation can nevertheless be uniquely determined. In particular, consistent with the claim of Uffink and Valente that there is “no time-asymmetric ingredient” in its derivation, the Boltzmann equation is shown to be time-reversal symmetric. The (...) proof is couched on the “ab initio” axiomatic approach to the classical statistical mechanics recently developed. Implications relevant for the physical interpretation of the Boltzmann H-theorem and the phenomenon of decay to kinetic equilibrium are pointed out. (shrink)