Normally, the perception of complete visual shapes given incomplete sensory evidence can be explained by interpolation; i.e., by the smooth monotonic connection of literally represented contour stimuli. However, in limiting conditions (e.g., the Gerbino illusion pattern) such a connection is impossible, forcing the visual system to either violate smoothness and monotonicity constraints or relax the literal representation assumption. I review evidence that figural completion may involve visual approximation rather than interpolation, and discuss the implications of such a view for perceptual theory.

In the Gerbino illusion a regular but coincidentally occluded polygon appears distorted. Such a display represents a critical condition for amodal completion (AC), in which the smooth continuations of contour fragments—however small—conflict with their possible monotonic interpolation. Smoothness and monotonicity are considered the fundamental constraints of AC at the contour level. To account for the Gerbino illusion we contrasted two models derived from alternative AC frameworks: visual interpolation , based on the literal representation of contour fragments, vs. visual approximation , which tolerates a small misorientation of contour fragments, compatible with smoothness and monotonicity constraints. To measure the perceived misorientation of sides of coincidentally occluded angles we introduced a novel technique for analyzing data from a multiple probe adjustment task. An unsupervised cluster analysis of errors in extrapolation and tilt adjustments revealed that the distortion observed in the Gerbino illusion is consistent with visual approximation and, in particular, with the concatenation of misoriented and locally shrinked amodally completed angles. Implications of our technique and obtained results shed new light on visual completion processes.

In the revolutionary year 1968, the Institute of Psychology of the University of Trieste directed by Gaetano Kanizsa published a collective volume to celebrate the 70th birthday of Cesare L. Musatti. Kanizsa devoted the opening article to the empirical refutation of an argument developed by Musatti in Structure and experience in perceptual phenomenology. Musatti held that the debate between rationalist and empiricist theories of perception was not scientific, since a crucial experiment on the role of past experience is-in principle-impossible. Besides rejecting his mentor's argument on logical grounds, Kanizsa produced a parade of visual effects to demonstrate that in several conditions (involving object formation and camouflage, Petter's rule, phenomenal transparency, shape recognition, motion organization) actual perception violates expectations based on familiarity with specific objects. The empirical refutation of expectations based on past experience was recurrent in Kanizsa's subsequent production and represents a lively topic of current perceptual science, though Musatti's smile is still here.

Over the last years, several studies have suggested a possible link between dyslexia and deficits in low-level visual processing (e.g., excessive crowding). At the same time, specially designed “dyslexia-friendly” fonts appeared on the market. This class of fonts presents two main features: the particular graphic characteristics of the letterform designed to avoid confusion between similarly shaped letters, and wider inter-letter and inter-word spacing to limit crowding. The literature testing the efficacy of “dyslexia-friendly” fonts in improving reading accuracy and increasing reading speed is controversial. We evaluated the impact of letterform (with vs. without dyslexia-friendly graphic features), inter-letter spacing (standard vs. increased), and inter-word spacing (standard vs. increased) on reading accuracy and speed. Two groups of 64 children each, with and without dyslexia, read aloud 8 equivalent texts. The data collected failed to show any effect from the letterform. As regards spacing, the data showed that reading speed is impaired by an increase in inter-letter spacing not combined with an adequate increase in inter-word spacing.

Amodal completion (AC) is analyzed, by looking at its historical roots and persisting conceptual difficulties. Looking at the origin of the concept, it becomes clear that it is not equivalent to perception of occluded parts. The role of fragment incompleteness is discussed, to clarify that it cannot be taken as a necessary factor for eliciting AC. The standard view of AC, depicted as a set of processes that extrapolate from veridically represented image fragments, is evaluated and rejected on the basis of evidence that AC modifies also modal parts. The theoretical importance of AC phenomena and their potential to reveal the inner forces of perceptual organization are emphasized, with specific reference to the minimum principle. Instances in which AC might be expected but does not occur are examined, to define the limits of such an integrative process.

We report two experiments on the role of mid-level processes in image segmentation and completion. In the primed matching task of Experiment 1, a cue→prime sequence was presented before the imperative stimulus consisting of target shapes with positive versus negative contour curvature polarity and one versus two axes of mirror symmetry. Priming shapes were included in two composite occlusion displays with the same T-junction information and different geometric features supporting a distinct balance between completion and mosaic solutions. A cue, either congruent or incongruent with targets, preceded the presentation of the composite priming display. Matching performance was affected by primes in the expected direction, while cue congruency participated only in a marginally significant three-way interaction, and prime duration had no effect. In Experiment 2, the cue→prime sequence was replaced by a fixation cross to control for the priming effect obtained in Experiment 1. The study confirmed that contour connectability and curvature polarity are effective structural factors capable of competing with symmetry in mid-level image segmentation and completion processes.

We used a cross-modal priming paradigm to evoke a biphasic effect in visual short-term memory. Participants were required to match the memorandum (a visual shape, either spiky or curvy) to a delayed probe (a shape belonging to the same category). In two-thirds of trials the sequence of shapes was accompanied by a task-irrelevant sound (either tzk or upo, cross-modally correspondent to spiky and curvy shape categories, respectively). The biphasic effect occurred when a congruent vs. incongruent sound was presented 200ms after the memorandum, while it did not occur when the sound was presented 200ms before or simultaneously with it. The biphasic pattern of recognition sensitivities was revealed by an interaction between cross-modal congruency and probe delay, such that sensitivity was higher for visual shapes paired with a congruent rather than incongruent sound with a 300-ms delay, while the opposite was true with a 1300-ms delay. We suggest that this biphasic pattern of recognition sensitivities was dependent on the task-irrelevant sound activating different levels of shape processing as a function of the relative timing of sound, memorandum, and probe.

Ship design review (DR) involves extensive collaborative and participatory processes and requires all DR actors (designers, stakeholders, endusers) to manage a large complex decision space in addition to coping with heavy cognitive demands. Here, we present a novel system whose purpose is to optimize the balance between ship DR complexity and the users' cognitive effort. The system exploits the power of interactive multi-user immersive 3D environments based on efficient immersive Virtual Reality Mock-Ups (VRMU) obtained directly from 3D CAD models. The remote multi-user cooperative interaction is supported by tools like Oculus Rift and Oculus Touch, as well as by avatars to overcome geographic distance and increase social proximity. This will likely facilitate joined decision processes and, through enaction, the visualization of environmental features (error/feature detection, information search), thus promoting the project development towards success.

Perceptual learning can occur for a feature irrelevant to the training task, when it is sub-threshold and outside of the focus of attention (task-irrelevant perceptual learning, TIPL); however, TIPL does not occur when the task-irrelevant feature is supra-threshold. Here, we asked the question whether TIPL occurs when the task-irrelevant feature is sub-threshold but within the focus of spatial attention. We tested participants in three different discrimination tasks performed on a 3-dot stimulus: a horizontal Vernier task and a vertical bisection task (during pre- and post-training sessions), and a luminance task (during training). In Experiment 1 we found that attending to luminance differences within the same stimulus that contains a sub-threshold horizontal offset (an irrelevant feature during training) does not preclude TIPL, as revealed by an improvement in the Vernier task, but not in the bisection task. This conclusion was confirmed in Experiment 2, in which the 3-dot stimulus used during training did not include a horizontal offset.

The ability to discriminate the trajectories of moving objects is highly adaptive and fundamental for physical and social interactions. Therefore, we could reasonably expect sensitivity to different trajectories already at birth, as a precursor of later communicative and defensive abilities. To investigate this possibility, we measured newborns' looking behavior to evaluate their ability to discriminate between visual stimuli depicting motion along different trajectories happening within the space surrounding their body. Differently from previous studies, we did not take into account defensive reactions, which may not be elicited by impending collision as newborns might not categorize approaching stimuli as possible dangers. In two experiments, we showed that newborns display a spontaneous visual preference for trajectories directed toward their body. We found this visual preference when visual stimuli depicted motion in opposite directions (approaching vs. receding) as well as when they both moved toward the peripersonal space and differed only in their specific target (i.e., the body vs. the space around it). These findings suggest that at birth human infants seem to be already equipped with visual mechanisms predisposing them to perceive their presence in the environment and to adaptively focus their attention on the peripersonal space and their bodily self.

In this paper, we study the impact of the human-readable documentation of Web ontologies on the ability of human users to agree on the membership of instances according to a given ontology. We first introduce a model of the problem and then present a user study, in which we measured the impact of documentation features in schema.org on the quality of annotations with n = 73 study participants. The paper concludes with a discussion of implications for ontology design in the context of the Semantic Web.

Abstract When the vertex of an occluded angle geometrically belongs to the side of the occluding surface, the occluded angle looks distorted. This characteristic effect of coincidental occlusion—called the Gerbino illusion—is consistent with the phenomenal rounding of angles observed under conditions of symmetrical occlusion. Both effects are robust and appear in static and dynamic displays. The Gerbino illusion differs from distortions observed in Poggendorff-like displays, runs against the tendency to global Prägnanz, and reveals important aspects of amodal completion processes. Alternative explanations based on visual interpolation and visual approximation are discussed. According to the approximation-based explanation, the possible discrepancy between internal models and the sensory input is perceptually represented as a phenomenal distortion.

According to action-perception coupling, extraretinal signals can disambiguate optic information, as in the contribution of head movements to the visual interpolation of twisted surfaces (Fantoni, Gerbino, Milani, Domini, JoV 2014). Going beyond approaches that exploit only the geometry of optic fragments, we focus here on the integration of self-generated haptic and optic information in 3D amodal completion. Does the precise shape of interpolated 3D surfaces depend on haptic information? We asked observers to reach and touch the nearest (visually amodal) portion of a convex 90° random-dot dihedron centrally occluded by a horizontal bar, glowing in the dark at eye height, with its virtual edge in the 500-550 mm depth range along the sagittal axis. As soon as the observer moved her hand, our HighRes Virtual Reality environment generated the 3D structure and a "magic finger", marked by a light point that provided a visual feedback of the index tip. The finger could go through the occluder and reach the amodally completed surface, conveying a tactile feedback. Using four coplanar gauge probes and four randomly interleaved staircases we measured the location of the (visually amodal) surface while the observer was (modally) touching it in three visual feedback conditions: normal (coincident with the actual finger position); 70-mm farther away; 70-mm closer. Relative to the normal feedback, the farther feedback molded the interpolated surface towards the good continuation solution, as if it were attracted by the objective index position (not the visually experienced one); while the closer feedback molded the interpolated surface farther away, in the direction of the minimal path solution. This is the first evidence of visuo-haptic 3D interpolation: when generating amodal surfaces, our "shape modeler" includes modal haptic information (derived from hand proprioception), going beyond geometric constraints defined by the co-circularity of optic fragments. Meeting abstract presented at VSS 2016

Respecting all constraints proposed by Firestone & Scholl (F&S), we have shown that perceived facial expressions of emotion depend on the congruency between bodily action (comfort/discomfort) and target emotion (happiness/anger) valence. Our studies challenge any bold claim against penetrability of perception and suggest that perceptual theory can benefit from demonstrations of how - under controlled circumstances - observer's states can mold expressive qualities.

Fantoni & Gerbino (2014) showed that subtle postural shifts associated with reaching can have a strong hedonic impact and affect how actors experience facial expressions of emotion. Using a novel Motor Action Mood Induction Procedure (MAMIP), they found consistent congruency effects in participants who performed a facial emotion identification task after a sequence of visually-guided reaches: a face perceived as neutral in a baseline condition appeared slightly happy after comfortable actions and slightly angry after uncomfortable actions. However, skeptics about the penetrability of perception (Zeimbekis & Raftopoulos, 2015) would consider such evidence insufficient to demonstrate that observer’s internal states induced by action comfort/discomfort affect perception in a top-down fashion. The action-modulated mood might have produced a back-end memory effect capable of affecting post-perceptual and decision processing, but not front-end perception. Here, we present evidence that performing a facial emotion detection (not identification) task after MAMIP exhibits systematic mood-congruent sensitivity changes, rather than response bias changes attributable to cognitive set shifts; i.e., we show that observer’s internal states induced by bodily action can modulate affective perception. The detection threshold for happiness was lower after fifty comfortable than uncomfortable reaches; while the detection threshold for anger was lower after fifty uncomfortable than comfortable reaches. Action valence induced an overall sensitivity improvement in detecting subtle variations of congruent facial expressions (happiness after positive comfortable actions, anger after negative uncomfortable actions), in the absence of significant response bias shifts. Notably, both comfortable and uncomfortable reaches impact sensitivity in an approximately symmetric way relative to a baseline inaction condition. All of these constitute compelling evidence of a genuine top-down effect on perception: specifically, facial expressions of emotion are penetrable by action-induced mood. Affective priming by action valence is a candidate mechanism for the influence of observer’s internal states on properties experienced as phenomenally objective and yet loaded with meaning.