An Intuitive Physics Study on the Role of Mass in Horizontal Collisions

The participants in our experiment were asked to judge whether simulated horizontal collisions appeared to be “natural” or “unnatural”. We manipulated the simulated materials and the velocity ratio of two colliding objects. The results revealed a fair degree of consistency between predictions of Newtonian mechanics and the participants’ responses

"Invariants" in Koffka's Theory of Constancies in Vision: Highlighting Their Logical Structure and Lasting Value

Summary By introducing the concept of "invariants", Koffka (1935) endowed perceptual psychology with a flexible theoretical tool, which is suitable for representing vision situations in which a definite part of the stimulus pattern is relevant but not sufficient to determine a corresponding part of the perceived scene. He characterised his "invariance principle" as a principle conclusively breaking free from the "old constancy hypothesis", which rigidly surmised point-to-point relations between stimulus and perceptual properties. In this paper, we explain the basic terms and assumptions implicit in Koffka's concept, by representing them in a set-theoretic framework. Then, we highlight various aspects and implications of the concept in terms of answers to six separate questions: forms of invariants, heuristic paths to them, what is invariant in an invariant, roots of conditional indeterminacy, variability vs. indeterminacy, and overcoming of the indeterminacy. Lastly, we illustrate the lasting value and theoretical power of the concept, by showing that Koffka's insights relating to it do occur in modern perceptual psychology and by highlighting its role in a model of perceptual transparency

Visual Perception of Dynamic Properties and Events: Collisions and Throws

The central topic of this dissertation is visual perception of dynamic events. The topic is worth of interest, as witnessed by its long tradition in the history of Experimental Psychology, starting with the seminal work of Albert Michotte (1881 - 1965) on phenomenal causality. Thus, the topic I chose is not original in itself. However, a distinctive element of novelty in my dissertation is the use of Computer Graphics techniques as a means for creating realistic experimental stimuli in psychological experiments. Besides the advantage of reducing the gap between laboratory experiments and everyday experience, this may reveal the importance of experimental variables which traditionally have been ignored in research on visual perception of dynamic events. The reader should be informed that this dissertation is characterized by various lines of research, which are intrinsically connected with the central topic of visual perception of dynamic events. In some of the experiments, I investigate visual perception of dynamic events, whereas in others I investigate cognition of the same events. Two distinct dynamic events will be especially studied: horizontal collisions and throws. Moreover, the results of the experiments will be discussed not only in relation to their theoretical implications for psychological models, but also in relation to their potential applications to Physics education and Computer Graphics. As a result, the content of the dissertation is quite heterogeneous, but I hope to provide the reader with a broad and multidisciplinary perspective on the subject at hand. The dissertation is composed of five chapters, which may be divided into three groups. (i) In Chapters 1-3, after a presentation of the theoretical background of visual perception of dynamic events, I investigate the influence of dynamic properties of virtual objects on visual perception of horizontal collisions. The results of this research are important for the old and still active debate on phenomenal causality. (ii) In Chapter 4 I present a research on Naïve Physics of horizontal collisions between virtual spheres differing in simulated mass and velocity. In this chapter I take a more cognitive (rather than perceptual) perspective on dynamic events, investigating how people reason about the proposed physical event. (iii) In Chapter 5, I present a research on visual perception of virtual throwing animations, which are complex and rarely studied dynamic events. This chapter stands out for its multidisciplinary nature, as in it I discuss how the results can be applied to Computer Graphics. The research presented in this last chapter has been conducted as a part of my doctorate studies when I was a visiting PhD student at the Graphics, Vision, and Visualisation Group at Trinity College Dublin, where I collaborated with Professor Carol O’Sullivan and Doctor Ludovic Hoyet, who are computer scientists working on applications of visual perception to Computer Graphics. In more detail, in Chapter 1 I discuss the theoretical background of visual perception of dynamic events and phenomenal causality. Firstly, I focus on Michotte’s classical work. Secondly, I discuss some prominent issues which have been debated for a long time in this field of research. Lastly, I present White’s schema-matching model of visual perception of dynamic events, discussing its differences and similarities as compared with Michotte’s model. This chapter is intended to serve as a theoretical point of reference for the entire dissertation. In Chapter 2 I discuss the hypothesis that visually perceived dynamic properties of objects involved in dynamic events do influence visual perception of the dynamic events themselves. Firstly, I try to confute two popular arguments against this hypothesis. Then, I highlight the evolutionary advantage of visual perception of dynamic properties, discussing their possible influence on visual perception of dynamic events. Lastly, I discuss Runeson’s KSD model in relation to the presented hypothesis. In Chapter 3 I present three experiments which confirm the hypothesis discussed in Chapter 2. In particular, I show that simulated material (Experiment 1) and size (Experiments 2 and 3) of virtual objects involved in horizontal collisions strongly influence how observers perceive the event. I also discuss the theoretical implications of these findings by referring to Michotte’s and White’s models. In Chapter 4 I present a research on Naïve Physics of horizontal collisions. Firstly, I discuss the general importance of studying Naïve Physics for improving basic education in Physics. Secondly, I present Information Integration Theory and Functional Measurement methodology as suitable tools for the assessment of students’ intuitive knowledge of physical events, evidencing their advantages over multiple-choice surveys. Lastly, I present two experiments (conducted using Information Integration Theory and Functional Measurement) on Naïve Physics of horizontal collisions between simulated spheres differing in size, velocity, and material. The importance of the results for Physics instruction will also be discussed. Finally, in Chapter 5 I present a research on visual perception of edited virtual throwing animations. First I discuss the relations between visual perception of dynamic events (human motion in particular) and Computer Graphics. Then, I present two experiments on observers’ sensitivity to anomalies in realistic virtual throwing animations, discussing the importance of the results for videogames and movies industry

Visual Perception of Dynamic Properties and Events: Collisions and Throws

The central topic of this dissertation is visual perception of dynamic events. The topic is worth of interest, as witnessed by its long tradition in the history of Experimental Psychology, starting with the seminal work of Albert Michotte (1881 - 1965) on phenomenal causality. Thus, the topic I chose is not original in itself. However, a distinctive element of novelty in my dissertation is the use of Computer Graphics techniques as a means for creating realistic experimental stimuli in psychological experiments. Besides the advantage of reducing the gap between laboratory experiments and everyday experience, this may reveal the importance of experimental variables which traditionally have been ignored in research on visual perception of dynamic events. The reader should be informed that this dissertation is characterized by various lines of research, which are intrinsically connected with the central topic of visual perception of dynamic events. In some of the experiments, I investigate visual perception of dynamic events, whereas in others I investigate cognition of the same events. Two distinct dynamic events will be especially studied: horizontal collisions and throws. Moreover, the results of the experiments will be discussed not only in relation to their theoretical implications for psychological models, but also in relation to their potential applications to Physics education and Computer Graphics. As a result, the content of the dissertation is quite heterogeneous, but I hope to provide the reader with a broad and multidisciplinary perspective on the subject at hand. The dissertation is composed of five chapters, which may be divided into three groups. (i) In Chapters 1-3, after a presentation of the theoretical background of visual perception of dynamic events, I investigate the influence of dynamic properties of virtual objects on visual perception of horizontal collisions. The results of this research are important for the old and still active debate on phenomenal causality. (ii) In Chapter 4 I present a research on Naïve Physics of horizontal collisions between virtual spheres differing in simulated mass and velocity. In this chapter I take a more cognitive (rather than perceptual) perspective on dynamic events, investigating how people reason about the proposed physical event. (iii) In Chapter 5, I present a research on visual perception of virtual throwing animations, which are complex and rarely studied dynamic events. This chapter stands out for its multidisciplinary nature, as in it I discuss how the results can be applied to Computer Graphics. The research presented in this last chapter has been conducted as a part of my doctorate studies when I was a visiting PhD student at the Graphics, Vision, and Visualisation Group at Trinity College Dublin, where I collaborated with Professor Carol O’Sullivan and Doctor Ludovic Hoyet, who are computer scientists working on applications of visual perception to Computer Graphics. In more detail, in Chapter 1 I discuss the theoretical background of visual perception of dynamic events and phenomenal causality. Firstly, I focus on Michotte’s classical work. Secondly, I discuss some prominent issues which have been debated for a long time in this field of research. Lastly, I present White’s schema-matching model of visual perception of dynamic events, discussing its differences and similarities as compared with Michotte’s model. This chapter is intended to serve as a theoretical point of reference for the entire dissertation. In Chapter 2 I discuss the hypothesis that visually perceived dynamic properties of objects involved in dynamic events do influence visual perception of the dynamic events themselves. Firstly, I try to confute two popular arguments against this hypothesis. Then, I highlight the evolutionary advantage of visual perception of dynamic properties, discussing their possible influence on visual perception of dynamic events. Lastly, I discuss Runeson’s KSD model in relation to the presented hypothesis. In Chapter 3 I present three experiments which confirm the hypothesis discussed in Chapter 2. In particular, I show that simulated material (Experiment 1) and size (Experiments 2 and 3) of virtual objects involved in horizontal collisions strongly influence how observers perceive the event. I also discuss the theoretical implications of these findings by referring to Michotte’s and White’s models. In Chapter 4 I present a research on Naïve Physics of horizontal collisions. Firstly, I discuss the general importance of studying Naïve Physics for improving basic education in Physics. Secondly, I present Information Integration Theory and Functional Measurement methodology as suitable tools for the assessment of students’ intuitive knowledge of physical events, evidencing their advantages over multiple-choice surveys. Lastly, I present two experiments (conducted using Information Integration Theory and Functional Measurement) on Naïve Physics of horizontal collisions between simulated spheres differing in size, velocity, and material. The importance of the results for Physics instruction will also be discussed. Finally, in Chapter 5 I present a research on visual perception of edited virtual throwing animations. First I discuss the relations between visual perception of dynamic events (human motion in particular) and Computer Graphics. Then, I present two experiments on observers’ sensitivity to anomalies in realistic virtual throwing animations, discussing the importance of the results for videogames and movies industry.Il tema centrale di questa tesi è la percezione visiva degli eventi dinamici. L’argomento è degno d’interesse, come testimoniato dalla sua lunga tradizione nella storia della Psicologia Sperimentale, iniziata con il lavoro fondamentale di Albert Michotte (1881 - 1965) sulla causalità fenomenica. L’argomento che ho scelto non è dunque originale in sé. Tuttavia, un elemento di novità nella mia tesi è l’utilizzo di tecniche di Computer Grafica per creare stimoli sperimentali realistici in esperimenti psicologici. Oltre al vantaggio di ridurre il gap tra gli esperimenti di laboratorio e l’esperienza quotidiana, questo può rivelare l’importanza di variabili sperimentali che sono state tradizionalmente ignorate nella ricerca sulla percezione visiva degli eventi dinamici. Il lettore deve essere informato che questa tesi è caratterizzata da diverse linee di ricerca, che sono intrinsecamente connesse con il tema centrale della percezione visiva degli eventi dinamici. In alcuni esperimenti, indago la percezione visiva degli eventi dinamici, mentre in altri indago la cognizione degli stessi eventi. Vengono studiati due diversi eventi dinamici: collisioni orizzontali e lanci. Inoltre, i risultati degli esperimenti vengono discussi non solo in relazione alle loro implicazioni teoriche per i modelli psicologici, ma anche in relazione alle loro potenziali implicazioni nel campo dell’insegnamento della Fisica e nel campo della Computer Grafica. Di conseguenza, il contenuto di questa tesi è abbastanza eterogeneo, ma spero di fornire al lettore una prospettiva ampia e multidisciplinare sull’argomento in questione. Questa tesi è composta di cinque capitoli, che possono essere divisi in tre gruppi. (i) Nei capitoli 1-3, dopo una presentazione del background teorico sulla percezione visiva di eventi dinamici, indago l’influenza delle proprietà dinamiche degli oggetti virtuali sulla percezione visiva delle collisioni orizzontali. I risultati di questa ricerca sono importanti per l’antico e ancora vivo dibattito sulla causalità fenomenica. (ii) Nel Capitolo 4 presento una ricerca sulla Fisica Ingenua delle collisioni orizzontali tra sfere virtuali di cui verranno manipolate massa simulata e velocità. In questo capitolo assumo una prospettiva più cognitiva che percettiva, indagando come le persone ragionano sull’evento fisico proposto. (iii) Nel Capitolo 5, presento una ricerca sulla percezione visiva delle animazioni virtuali di lancio, che sono eventi dinamici complessi e poco studiati. Questo capitolo spicca per la sua natura multidisciplinare, poiché in esso discuto come i risultati possano essere applicati alla Computer Grafica. La ricerca presentata in quest’ultimo capitolo è stata condotta come parte dei miei studi di dottorato quando sono stato ospite del Graphics, Vision, and Visualisation Group al Trinity College Dublin, dove ho collaborato con la Professoressa Carol O’Sullivan ed il Dottor Ludovic Hoyet, che sono ingegneri informatici che lavorano alle applicazioni della percezione visiva alla Computer Grafica. Più nel dettaglio, nel Capitolo 1 discuto il background teorico della percezione visiva degli eventi dinamici e della causalità fenomenica. In primo luogo, mi focalizzo sul classico lavoro di Michotte. In secondo luogo, discuto alcuni importanti problemi che sono stati dibattuti per lungo tempo in questo campo di ricerca. Infine, presento lo “schema-matching model” di White sulla percezione degli eventi dinamici, discutendo le sue differenze e somiglianze con il modello di Michotte. Questo capitolo è concepito per servire da punto di riferimento teorico per l’intera tesi. Nel Capitolo 2 discuto l’ipotesi che le proprietà dinamiche (percepite visivamente) degli oggetti coinvolti in eventi dinamici influenzano la percezione visiva degli eventi dinamici stessi. In primo luogo, provo a confutare due popolari argomentazioni contro questa ipotesi. Poi, evidenzio il vantaggio evolutivo della percezione visiva delle proprietà dinamiche, discutendo la loro possibile influenza sulla percezione visiva degli eventi dinamici. Infine, discuto il modello KSD di Runeson in relazione all’ipotesi presentata. Nel Capitolo 3 presento tre esperimenti, i quali confermano l’ipotesi discussa nel Capitolo 2. In particolare, mostro che il materiale simulato (Esperimento 1) e la dimensione (Esperimenti 2 e 3) degli oggetti virtuali coinvolti nelle collisioni orizzontali influenzano fortemente come le persone percepiscono l’evento. Discuto anche le implicazioni teoriche di questi risultati, facendo riferimento ai modelli di White e di Michotte. Nel Capitolo 4 presento una ricerca sulla Fisica Ingenua delle collisioni orizzontali. In primo luogo, discuto l’importanza generale dello studio della Fisica Ingenua per migliorare l’insegnamento della Fisica elementare. In secondo luogo, presento la Teoria dell’Integrazione delle Informazioni e la metodologia della Misurazione Funzionale come strumenti adeguati per la valutazione della conoscenza ingenua degli eventi fisici da parte degli studenti, evidenziando i loro vantaggi rispetto ai questionari a scelta multipla. Infine, presento due esperimenti (condotti utilizzando la Teoria dell’Integrazione delle Informazioni e la Misurazione Funzionale) sulla Fisica Ingenua delle collisioni orizzontali tra sfere simulate che differiscono per dimensione, velocità, e materiale. Verrà anche discussa l’importanza dei risultati per l’insegnamento della Fisica. Infine, nel Capitolo 5 presento una ricerca sulla percezione visiva di animazioni virtuali di lancio modificate. Prima discuto le relazioni tra percezione visiva degli eventi dinamici (del movimento umano in particolare) e la Computer Grafica. Poi presento due esperimenti sulla sensibilità degli osservatori alle anomalie in animazioni virtuali di lancio realistiche, discutendo l’importanza dei risultati per l’industria dei videogiochi e dei film