Liliana Albertazzi

The School of Franz Brentano

Introduction. Brentano and his School: Reassembling the Puzzle L. Albertazzi, et al. 1. Franz Brentano (1838-1917) M. Libardi. Part I: The Pupils. 2. Anton Marty (1847-1914) L. Albertazzi. 3. Carl Stumpf (1848-1936) K. Schumann. 4. Alexius Meinong (1853-1920) D. Jacquette. 5. Christian von Ehrenfels (1859-1932) R. Fabian. 6. E. Husserl (1859-1938) L. Albertazzi. 7. Kazimierz Twardowski (1866-1938) R. Poli. Part II: Topics and Influences. 8. Act, Content, and Object W. Baumgartner. 9. Intentionality J. Brandl. 10. Higher-Order Objects P. Bozzi. 11. Logic in the Brentano School P. Simons. 12. Logic and the Sachverhalt B. Smith. 13. Truth Theories R. Poli. 14. Reism in the Brentanist Tradition J. Wolenski. 15. Theories of Values L. Dappiano. 16. From Kant to Brentano L. Albertazzi. Index of Topics. Index of Names.

The Ebbinghaus illusion in a fish (Xenotoca eiseni)

The tendency of fish to perceive the Ebbinghaus illusion was investigated. Redtail splitfins (Xenotoca eiseni, family Goodeidae) were trained to discriminate between two disks of different sizes. Then, fish were presented with two disks of the same size surrounded by disks of large or small size (inducers) arranged to produce the impression (to a human observer) of two disks of different sizes (in the Ebbinghaus illusion, a central disk surrounded by small inducers appears bigger than an identical one surrounded by large inducers). Fish chose the stimulus that, on the basis of a perception of the Ebbinghaus illusion, appeared deceptively larger or smaller, consistent with the condition of training. These results demonstrate that redtail splitfins tend to perceive this particular illusion. The results are discussed with reference to other related illusions that have been recently observed to be experienced by fish (such as the Navon effect), and with regard to their possible evolutionary implications.

Stereokinetic Shapes and Their Shadows

The visual space of phenomenal appearances has a complex geometry which cannot be reduced strictly to Euclidean or projective geometry. The distinctive nature of this space and its objects is evidenced paradigmatically by stereokinetic phenomena, which are perceptual objects in actual three-dimensional coming into being. Stereokinetic phenomena produce the appearance not only of corporeality but also, in certain circumstances, of shadows. By altering certain components of his experiments on the three-dimensional appearance of a truncated cone, in fact, Musatti discovered that on its white base floats some sort of shadow obscuring stretches of the white lines. These shadows are connected to phenomena of amodal presentations successively analysed by Kanizsa. The continuity of the unfolding in visual space of stereokinetic transformations produces a diversified series of percepts coming into being, shadows included, and highlights the role of configurational movement as a factor of formal unification, thereby proposing once again the hypothesis of assimilative factors as responsible for the field organisation of past experience.

The Semantics of Biological Forms

This study analyses how certain qualitative perceptual appearances of biological forms are correlated with expressions of natural language. Making use of the Osgood semantic differential, we presented the subjects with 32 drawings of biological forms and a list of 10 pairs of connotative adjectives to be put in correlations with them merely by subjective judgments. The principal components analysis made it possible to group the semantics of forms according to two distinct axes of variability: Harmony and dynamicity. Specifically, the nonspiculed, nonholed, and flat forms were perceived as harmonic and static; the rounded ones were harmonic and dynamic. The elongated forms were somewhat disharmonious and somewhat static. The results suggest the existence in the general population of a correspondence between perceptual and semantic processes, and of a nonsymbolic relation between visual forms and their adjectival expressions in natural language.

Emotion based classification of natural images

Images convey opinions and emotional messages in the communication process. With the increasing use of images in various scenarios, the area of opinion mining and sentiment analysis has recently received a huge burst of interest. In particular, in the context of social web the ability of identify different emotions in images might help providing diversification of results, thus proposing different viewpoints to users. In this paper we analyze which are the features (e.g., colors, texture) that are more strictly related to the emotional content of a picture, thus allowing a classification connected with the emotion conveyed by images. We present the results on a set of natural images in order to reduce as much as possible the interaction with content semantics.

Does monocular visual space contain planes

The issue of the existence of planes-understood as the carriers of a nexus of straight lines-in the monocular visual space of a stationary human observer has never been addressed. The most recent empirical data apply to binocular visual space and date from the 1960s (Foley, 1964). This appears to be both the first and the last time this basic issue was addressed empirically. Yet the question is of considerable conceptual interest. Here we report on a direct empirical test of the existence of planes in monocular visual space for a group of sixteen experienced observers. For the majority of these observers monocular visual space lacks a projective structure, albeit in qualitatively different ways. This greatly reduces the set of viable geometrical models. For example, it rules out all the classical homogeneous spaces (the Cayley-Klein geometries) such as the familiar Luneburg model. The qualitatively different behavior of experienced observers implies that the generic population might well be inhomogeneous with respect to the structure of visual space.

Cross-modal associations between materic painting and classical Spanish music

The study analyses the existence of cross-modal associations in the general population between a series of paintings and a series of clips of classical (guitar) music. Because of the complexity of the stimuli, the study differs from previous analyses conducted on the association between visual and auditory stimuli, which predominantly analyzed single tones and colors by means of psychophysical methods and forced choice responses. More recently, the relation between music and shape has been analyzed in terms of music visualization, or relatively to the role played by emotion in the association, and free response paradigms have also been accepted. In our study, in order to investigate what attributes may be responsible for the phenomenon of the association between visual and auditory stimuli, the clip/painting association was tested in two experiments: the first used the semantic differential on a unidimensional rating scale of adjectives; the second employed a specific methodology based on subjective perceptual judgments in first person account. Because of the complexity of the stimuli, it was decided to have the maximum possible uniformity of style, composition and musical color. The results show that multisensory features expressed by adjectives such as “quick,” “agitated,” and “strong,” and their antonyms “slow,” “calm,” and “weak” characterized both the visual and auditory stimuli, and that they may have had a role in the associations. The results also suggest that the main perceptual features responsible for the clip/painting associations were hue, lightness, timbre, and musical tempo. Contrary to what was expected, the musical mode usually related to feelings of happiness (major mode), or to feelings of sadness (minor mode), and spatial orientation (vertical and horizontal) did not play a significant role in the association. The consistency of the associations was shown when evaluated on the whole sample, and after considering the different backgrounds and expertise of the subjects. No substantial difference was found between expert and non-expert subjects. The methods used in the experiment (semantic differential and subjective judgements in first person account) corroborated the interpretation of the results as associations due to patterns of qualitative similarity present in stimuli of different sensory modalities and experienced as such by the subjects. The main result of the study consists in showing the existence of cross-modal associations between highly complex stimuli; furthermore, the second experiment employed a specific methodology based on subjective perceptual judgments.

The Ontology of Perception

The chapter deals with the ontology of pereption and presents the basis of a science of appearances. Even when current perceptual science deals with qualitative aspects of experience, it almost exclusively explains perceptions in terms of quantitatively understood stimuli. Given that almost no aspect of perception is quantitative in nature, a properly qualitative understanding of perceptual experience is needed. Accordingly, the chapter presents the main aspects of such a qualitative understanding of perception.

The Müller-Lyer illusion in the teleost fish Xenotoca eiseni

In the Müller-Lyer illusion, human subjects usually see a line with two inducers at its ends facing outwards as longer than an identical line with inducers at its ends facing inwards. We investigate the tendency for fish to perceive, in suitable conditions, line length according to the Müller-Lyer illusion. Redtail splitfins (Xenotoca eiseni, family Goodeidae) were trained to discriminate between two lines of different length. After reaching the learning criterion, the fish performed test trials, in which they faced two lines (black or red) of identical length, differing only in the context in terms of arrangement of the inducers, which were positioned at the ends of the line, either inward, outward, or perpendicular. Fish chose the stimulus that appear to humans as either longer or shorter, in accordance with the prediction of the Müller-Lyer illusion, consistently with the condition of the training. These results show that redtail splitfins tend to be subject to this particular illusion. The results of the study are discussed with reference to similar studies concerning the same illusion as recently observed in fish. Contrasting results are presented. The significance of the results in light of their possible evolutionary implications is also discussed.

Relief articulation techniques

We consider techniques used in the articulation of pictorial relief. The related ‘cue’ best known to vision science is ‘shading’. It is discussed in terms of an inverse optics algorithm known as ‘shape from shading’. However, the familiar techniques of the visual arts count many alternative cues for the articulation of pictorial relief. From an art technical perspective these cues are well known. Although serving a similar purpose as shading proper, they allow a much flatter value scale, making it easier to retain the picture plane, or major tonal areas. Vision research has generally ignored such methods, possibly because they lack an obvious basis in ecological optics. We attempt to rate the power of various techniques on a common ‘shading scale’. We find that naive observers spontaneously use a variety of cues, and that several of these easily equal, or beat, conventional shading. This is of some conceptual interest to vision science, because shading has a generally acknowledged ecological basis, whereas the alternative methods lack this.