Colour appearance is affected not only by perceptual but also by linguistic context

Terminology is a crucial problem in science, since quite often the terms used to denote theoretical concepts are directly taken from the vocabulary of common words, which usually have multiple meanings. To solve this problem, scientists must operationalize the theoretical concepts they use but, in psychology, sometimes, this can be a difficult task, since the meaning of the terms used to give the instructions to observers can interfere with the spontaneous meaning that observers give to those terms. Starting from some empirical observations, we show that colour appearance is affected not only by the perceptual but also by the linguistic context

The perceptual contrast of impossible shadow edges

Luminance ratios along shadow edges remain the same even when they cross reflectance borders. According to Gilchrist (1988, Perception & Psychophysics 43 415 ^ 424) this so-called ratio-invariance property is a crucial factor in the perception of shadows. However, Soranzo and Agostini (2004, Perception 33 1359 ^ 1368) suggested that in some conditions (named `impossible shadows'), a luminance pattern might still be perceived as a shadow even if the ratio-invariance property along its edge is violated. This can occur when an edge is collinear with another edge (contextual edge) which incorporates it, shares the same polarity, and generates a larger ratio. The hypothesis that impossible shadows are actually perceived as shadows is here tested by comparing the perceptual contrast of a luminance edge in the absence of a contextual edge (control condition) to that of both possible shadow edges (where the contextual and mediating edge share the same ratio) and impossible shadow edges (where the ratio of the contextual edge is larger rather than that at the mediating edge). We found that the perceived contrast of luminance edges shrinks in both possible and impossible shadow conditions rather than in the control condition. This evidence supports the hypothesis that a luminance pattern might be perceived as a shadow even when the ratio-invariance property is violated

Luminance gradients, perceived illumination, and lightnes perception

1nonenoneAGOSTINI T.; GALMONTE A.Agostini, Tiziano; Galmonte, Alessandr

Contrasting a Misinterpretation of the Reverse Contrast

open access articleThe reverse contrast is a perceptual phenomenon in which the effect of the classical simultaneous lightness contrast is reversed. In classic simultaneous lightness contrast configurations, a gray surrounded by black is perceived lighter than an identical gray surrounded by white, but in the reverse contrast configurations, the perceptual outcome is the opposite: a gray surrounded by black appears darker than the same gray surrounded by white. The explanation provided for the reverse contrast (by different authors) is the belongingness of the gray targets to a more complex configuration. Different configurations show the occurrence of these phenomena; however, the factors determining this effect are not always the same. In particular, some configurations are based on both belongingness and assimilation, while one configuration is based only on belongingness. The evidence that different factors determine the reverse contrast is crucial for future research dealing with achromatic color perception and, in particular, with lightness induction phenomena

SNARC-like compatibility effects for physical and phenomenal magnitudes: A study on visual illusions

Both numerical and non-numerical magnitudes elicit similar Spatial-Numerical Association of Response Codes (SNARC) effects, with small magnitudes associated with left hand responses and large magnitudes associated with right hand responses (Dehaene, Bossini, Giraux, 1993). In the present study, we investigated whether the phenomenal size of visual illusions elicits the same SNARC-like effect revealed for the physical size of pictorial surfaces. Four experiments were conducted by using the Delboeuf illusion (Experiment 1) and the Kanizsa triangle illusion (Experiments 2, 3 & 4). Experiment 1 suggests the presence of a SNARC-like compatibility effect for the physical size of the inducers, while this effect was not revealed for the phenomenal size of the induced elements, possibly masked by a stronger effect of the inducers. A SNARC-like effect for the phenomenal size of the Kanizsa triangle was revealed when participants directly compared the size of the triangles (Experiment 4). Conversely, when participants performed an indirect task (orientation judgment), the SNARC-like effect was present neither for the illusory nor for the physical displays (Experiments 2 & 3). The effect revealed for the size of illusory triangles was comparable to that of real triangles with physical contours, suggesting that both phenomenal and physical magnitudes similarly elicit SNARC-like effects

Panic disorder patients and healthy people differently identify their own heart frequency through sound

The file attached to this record is the Publisher's version. Open access journal.The ability to detect the perceptual cues related to cardiac activity is an important aspect related to the onset and maintenance of some psychopathological disorders, such as panic disorder. We tested two groups – panic disorder (PD) patients and healthy participants – in order to examine the ability to estimate participants’ own heart frequency. We used an auditory identification task, based on the administration of auditory tracks representative of ecological sounds of heartbeat. Results showed that all healthy participants underestimated their own heart frequency, whereas the majority of PD patients overestimated it. This different response tendency could influence the development of psychopathologies such as panic disorder. These outcomes suggest the possible development of training for PD patients based on the use of auditory stimulation

Further Empirical Evidence on Patrick Hughes’ Reverspectives: A Pilot Study

open access articleReverspectives are paintings created by the English artist Patrick Hughes. They are 3D structures, for example, pyramids or prisms, which elicit an illusory depth perception that corresponds to the reverse of the physical depth layout. Rogers and Gyani state that “the perspective information provided by a simple grid of vertical and horizontal lines on a slanting surface can be just as powerful as the information provided by a rich, naturalistic scene”. The present experiment was aimed to further investigate this perspective reversal. Three independent variables were manipulated: (1) texture components (i.e., vertical, horizontal, and oblique lines components), (2) texture spatial arrangement (i.e., Hughes-type “perspective” grid vs. equidistant “no perspective” grid), and (3) illumination direction (i.e., homogeneous illumination, light from above, and light from below). The dependent variable was the “critical distance”, namely, the distance between an approaching observer and the stimulus at which the illusory depth perception of concavity/convexity switched to the actual perception of convexity/concavity. The results showed that a stronger illusion is elicited by: (a) a Hughes-type texture spatial arrangement; (b) a complete grid texture composition, having both vertical and horizontal, and oblique components; and (c) illumination from below, as opposed to the condition in which light is coming from above

Loudness, but not shot power, influences simple reaction times to soccer penalty sounds

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Open access journalObjective: The aim of the present study was to investigate how ecological sport sounds (i.e., foot-ball impacts of soccer penalty kicks) affect simple reaction times. Design: Three within-subjects, simple reaction time experiments were carried out; they differed among each other for the manipulations performed on the stimuli. Method: In Experiment 1, the loudness of the stimuli was manipulated; instead, in Experiment 2 and 3 shot power was manipulated, using as stimuli impacts of shots with different speeds. Results: The results highlighted an inverse relation between stimuli loudness and reaction times; instead, the natural differences among shots with different power were not sufficient to influence reaction times. Conclusions: Sounds associated to different shot power seem to differ in parameters which are not actually relevant for simple reaction times. Future studies should further investigate on similar issues, better clarifying whether the properties of ecological sounds can naturally influence reaction times

Perceptual belongingness determines the direction of lightness induction depending on grouping stability and intentionality

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI linkContrast and assimilation are two opposite perceptual phenomena deriving from the relationships among perceptual elements in a visual field. In contrast, perceptual differences are enhanced; while, in assimilation, they are decreased. Indeed, if contrast or assimilation occurs depends on various factors. Interestingly, Gestalt scientists explained both phenomena as the result of perceptual belongingness, giving rise to an intriguing paradox. Benary suggested that belongingness determines contrast; conversely, Fuchs suggested that it determines assimilation. This paradox can be related both to the grouping stability (stable/multi-stable) and to the grouping intentionality (intentional/non-intentional). In the present work we ran four experiments to test whether the contrast/assimilation outcomes depend on the above-mentioned variables. We found that, intentionality and multi-stability elicit assimilation; while, non-intentionality and stability elicit contrast