Sensation and perception

One of the oldest and most difficult questions in science is how we are able to develop an awareness of the world around us from our senses. Topics covered under the title of, 'Sensation and perception' address this very question. Sensation encompasses the processes by which our sense organs (e.g. eyes, ears etc.) receive information from our environment, whereas perception refers to the processes through which the brain selects, integrates, organises and interprets those sensations. The sorts of questions dealt with by psychologists interested in this area include: 'how does visual information get processed by the brain?', 'how is it that I am able to recognise one face out of many many thousands?', and 'what causes visual illusions to occur?: Within New Zealand there are a number of researchers studying visual perception specifically and their research interests range from understanding the biologica

The perception of surface layout during low level flight

Although it is fairly well established that information about surface layout can be gained from motion cues, it is not so clear as to what information humans can use and what specific information they should be provided. Theoretical analyses tell us that the information is in the stimulus. It will take more experiments to verify that this information can be used by humans to extract surface layout from the 2D velocity flow field. The visual motion factors that can affect the pilot's ability to control an aircraft and to infer the layout of the terrain ahead are discussed

Visual slant underestimation

Observers frequently underestimate the in-depth slant of rectangles under reduction conditions. This also occurs for slanted rectangles depicted on a flat display medium. Perrone (1982) provides a model for judged slant based upon properties of the 2-D trapezoidal projection of the rectangle. Two important parameters of this model are the angle of convergence of the sides of the trapezoid and the projected length of the trapezoid. This model was tested using a range of stimulus rectangles and found that the model failed to predict some of the major trends in the data. However, when the projected width of the base of the trapezoid projection was used in the model, instead of the projected length, excellent agreement between the theoretical and obtained slant judgements resulted. The good fit between the experimental data and the new model predictions indicates that perceived slant estimates are highly correlated with specifiable features in the stimulus display

A single mechanism can explain the speed tuning properties of MT and V1 complex neurons

A recent study by Priebe et al., (2006) has shown that a small proportion (27%) of primate directionally selective, complex V1 neurons are tuned for the speed of image motion. In this study, I show that the weighted intersection mechanism (WIM) model, which was previously proposed to explain speed tuning in middle temporal neurons, can also explain the tuning found in complex V1 neurons. With the addition of a contrast gain mechanism, this model is able to replicate the effects of contrast on V1 speed tuning, a phenomenon that was recently discovered by Priebe et al., (2006). The WIM model simulations also indicate that V1 neuron spatiotemporal frequency response maps may be asymmetrical in shape and hence poorly characterized by the symmetrical two-dimensional Gaussian fitting function used by Priebe et al., (2006) to classify their cells. Therefore, the actual proportion of speed tuning among directional complex V1 cells may be higher than the 27% estimate suggested by these authors

Visual slant misperception and the Black-Hole landing situation

A theory which explains the tendency for dangerously low approaches during night landing situations is presented. The two dimensional information at the pilot's eye contains sufficient information for the visual system to extract the angle of slant of the runway relative to the approach path. The analysis is depends upon perspective information which is available at a certain distance out from the aimpoint, to either side of the runway edgelights. Under black hole landing conditions, however, this information is not available, and it is proposed that the visual system use instead the only available information, the perspective gradient of the runway edgelights. An equation is developed which predicts the perceived approach angle when this incorrect parameter is used. The predictions are in close agreement with existing experimental data

On the Estimation of Euler Equations in the Presence of a Potential Regime Shift

The concept of a peso problem is formalized in terms of a linear Euler equation and a nonlinear marginal model describing the dynamics of the exogenous driving process. It is shown that, using a threshold autoregressive model as a marginal model, it is possible to produce time-varying peso premia. A Monte Carlo method and a method based on the numerical solution of integral equations are considered as tools for computing conditional future expectations in the marginal model. A Monte Carlo study illustrates the poor performance of the generalized method of moment (GMM) estimator in small and even relatively large samples. The poor performance is particularly acute in the presence of a peso problem but is also serious in the simple linear case.peso problem; Euler equations; GMM; threshold autoregressive models

DALLA CORTE COSTITUZIONALE UNA POSSIBILE SOLUZIONE ALLA TORMENTATA QUESTIONE DEL CONTRADDITTORIO ENDOPROCEDIMENTALE TRIBUTARIO

La parabola del contraddittorio endoprocedimentale nel procedimento tributario di accertamento sembrava essersi conclusa con le sentenze nn. 19667 e 19668 del 2014, rese a sezioni unite della Suprema Corte, mediante il definitivo riconoscimento dell\u2019immanenza dello stesso al nostro sistema. Tuttavia le stesse sezioni unite con la sentenza n. 24283 del 2015 hanno riaperto la problematica, trovando la soluzione, giudicata opinabile in dottrina, di confinare la generalizzata obbligatorieta` del contraddittorio ai soli tributi cd. \u201carmonizzati\u201d. L\u2019intendimento di definire la questione alla luce dei principi europei, pero` , poteva forse suggerire una diversa soluzione, e cioe` una via che, recependo i criteri ermeneutici suggeriti dalla Corte costituzionale con la sentenza n. 132 del 2015, cercasse di trovare all\u2019interno del nostro ordinamento delle norme di principio che, in via potenziale, ed interpretate alle luce dei criteri provenienti dalla Corte di giustizia, potessero legittimare l\u2019applicazione del contraddittorio in via generalizzata, evitando cos\u131` le inevitabili difficolta` pratiche e teoriche generate dalla scelta di confinare l\u2019istituto ai soli tributi armonizzat