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ORIGINS OF SENSITIVITY TO PHYSICAL CAUSALITY AND ANIMACY: Evidence from newborn babies and newly-hatched chicks
No full textIdentifying animated subjects and causal relations between them ought to be fundamental for the survival of animals. Humans' striking ability to attribute “animacy” (i.e. the capability of an object to have self-produced motion and of being a causal-agent) and causal relations to moving objects solely on the basis of their pattern of motion is well attested (Heider and Simmel, 1944; Michotte, 1963; Schlottmann, Ray, Mitchell and Demetriou, 2006).
Nothing is known, though, about the origin of this sensitivity, which could be either implicit or the outcome of some learning processes. A further source of debate concerns whether this capability is present both in human and non-human animals.
For such reasons, the purpose of this thesis was to investigate the sensitivity to physical causality from a comparative perspective, employing both newborn babies and newly-hatched domestic chicks (Gallus gallus) as experimental subjects. Moreover, chicks’ sensitivity to self-propelled motion as a cue to animacy attributions was investigated.
Sensitivity to physical causality in a comparative perspective
Attribution of causality (i.e. appreciation of the interaction between any two events in terms of a cause-effect relationship) appears to be a powerful mechanism for perceiving every day experiences, in such a way we may make sense of almost any aspect of the physical world.
Understanding causal representations has long been a challenge both for philosophers (Aristotele, Physics) and psychologists (see Sperber, Premack and Premack, 1995). Psychological research has both focused on exploring higher-level cognitive processing (i.e., the dynamics of causal inferences, Sperber et al., 1995), whilst at the same time much critical work on causality has concentrated on the role of perceptual processing (Michotte, 1963).
As regards the latter perspective, the earliest ideas were put forward by Michotte (1963), who described the most well known example of perceptual causality, the “Launching Event”. In this event an object, “A”, starts moving towards a second object, “B”, in a straight line and at constant speed. When A comes into contact with B, A stops moving and B moves off in the same direction and at the same or slightly lesser speed in which object A had been moving. When this event is viewed, most people see object A “launching” B, thus causing its movement. According to Michotte, the “causal impression” triggered by the Launching Event is automatically produced by a “perceptual input analyzer”, that would provide an original idea of cause: a causal connection is experienced as a result of what is a perceptual process, rather than a conceptually mediated inference (Michotte, 1963).
The fact that this perception is hardly affected by higher-level beliefs or intentions (whereas it seems to depend on a highly constrained collection of visual cues; e.g. Choi and Scholl, 2004, 2006; Schlottmann et al., 2006; White, 2006), would support a precocial ontogenetic (and phylogenetic) origin. Michotte himself, even though his work was based on verbal reports by adult observers, took a strong nativistic position on the origin of causal representations, claiming that the perceptual mechanism for causal impressions was innate, and furthermore that the output of this mechanism was the source of all subsequently developing causal representations (Michotte, 1963).
Recently, a growing interest in the earliest causal representations has produced a range of experimental data in developmental studies (Leslie, 1984; Leslie and Keeble, 1987; Cohen and Amsel, 1998; Cohen and Oakes, 1993; Cohen, Rundell, Spellman and Cashon, 1999; Oakes, 1994; Oakes and Cohen, 1990), such data used in support of two very different models of the origin of causal perception. On the one hand, Leslie and colleagues (Leslie and Keeble, 1987) suggested that there would be an innate, domain-specific visual module that operates ‘‘automatically and incorrigibly upon the spatio-temporal properties of events yet producing abstract descriptions of their causal structure” (Leslie, 1988). In contrast, Cohen and colleagues suggested a constructivist account: the perception of causality would be demonstrably not innate and not domain specific (Cohen and Amsel, 1998; Cohen, Chaput and Cashon, 2002). The causality of events could be either perceived as a result of perceptual and cognitive development (Oakes and Cohen, 1990) or constructed during development from non-causal resources within core cognition (Carey, 2009).
Until now, however, perception of physical causality has never been investigated in subjects under conditions in which previous experiences have been effectively controlled for (e.g., in newborn babies). Moreover, nothing is known specifically about the capability to perceive physical causality in animal species other than our own.
For these reasons this thesis was aimed at investigating spontaneous preferences for physical causality both in newborn babies and in newly-hatched domestic chicks.
The domestic chick seemed to be an ideal subject to address this issue, since it is a highly visual and precocial species, and has shown capable of perceiving shapes defined by motion information alone, much as humans can (e.g. Mascalzoni, Regolin and Vallortigara, 2009; Vallortigara, Regolin and Marconato, 2005).
Two experiments were conducted in which chicks’ spontaneous preferences for a Causal Stimulus (i.e., Launching Effect) vs a Non-Causal Stimulus were assessed.
All subjects came from eggs incubated and hatched in total darkness under controlled conditions; this prevented any prior visual experience before testing. On their second day of life, chicks underwent a spontaneous preference test, in which they had to choose between two video animations (a Causal Animation and a Non-Causal Animation), simultaneously presented at the two opposite ends of a runway. At the beginning of the test chicks were taken individually from the dark hatchery and placed in the central sector of the runway, which was virtually subdivided into three areas. The behaviour of the chick was observed for a total of six consecutive minutes. In order to approach one of the testing animations, the subject had to leave the central area and enter one of the side areas. If the chick remained in the mid compartment, this was deemed to indicate no preference, whereas if it went into an end-side compartment this was regarded as a preference for the stimulus placed at that end of the runway.
All the stimuli were video animations involving two square-shaped objects of the same dimension and colour. For the Launching Stimulus one of the 2 objects (“A”) started to move towards a second, stationary object (“B”). Immediately after contact, A stopped and B moved off in the same direction and at the same speed that A previously showed. Thus, when seen together this stimulus reproduced the typical Michotte’s Launching Effect, in which adult humans report as seeing a physical-causality relationship between the two movements.
In Exp. 1, a “Delay Stimulus” was used as the Non-Causal Stimulus. It was identical to the Launching Stimulus except for a 2-sec-delay between the moment of contact and the initiation of motion of object B: such a delay is known to abolish any impression of physical causality in adult humans (Michotte, 1963). The Non-Causal Stimulus employed in Exp. 2, instead, was a “Passing” Stimulus in which the initial moving object (A) moved towards the stationary object B, passed in front of it and reached the final position occupied by B at the end of the Launching sequence. In this animation no physical causality was implied but the spatio-temporal continuity typical of the Launching Effect was preserved.
In Exp. 1, thus, chicks preference between a Launching and a Delay Stimulus was tested, whether in Exp. 2 chicks were asked to choose between a Launching and a Passing Stimulus.
The results did not reveal any spontaneous preference for either stimuli in chicks shortly after hatching. Therefore, it seems that newly-hatched domestic chicks have no preferences for approaching a causal event compared to a non-causal event.
The other branch of the thesis dealt with newborn babies’ sensitivity to physical causality.
Three experiments were conducted, all employing an infant-control preferential looking technique which allowed for the testing of newborns’ spontaneous preferences for a Causal vs a Non-Causal stimulus by measuring the length of time of their fixations on the stimuli.
In this procedure, a baby was sat on the experimenter’s lap in front of a monitor. Two testing stimuli were presented simultaneously, on the left and the right side of the monitor. Each newborn was given two paired presentations of the test stimuli in which the position of the stimuli was reversed (the initial left-right order of presentation was counterbalanced across subjects). The duration of the infant’s fixations on each stimulus was recorded on-line and subsequently re-coded off-line by a second experimenter. Each trial ended when the newborn did not fixate on the display for at least 10 s.
In Exp. 1 newborns’ spontaneous preference for a Launching Stimulus vs a Non-Causal Control Stimulus was investigated. Two computer-presented animation sequences were created, each sequence featuring two identical gray discs (“A” and “B”). The Launching video animation had the usual spatio-temporal features of a Launching Effect (Michotte, 1963). Both discs, moreover, moved with identical speed and covered the same distance. As described previously, in this sort of display adult subjects perceive disc A as “launching” disc B hence causing its movement. The Non-Causal Control animation was identical to the Launching one except for the fact that, maintaining the same starting positions, the order of the displacement of the two discs was swapped temporally: thus B moved first and A started its movement only after B had stopped. In this sequence any physical causality between the movements of the two discs was disrupted (no contact occurred between A and B), whereas distances travelled and perceptual features of the two discs were identical to those of the Launching Stimulus.
With regard to the data, newborns’ fixation times showed that babies looked significantly longer at the Launching Stimulus.
These results seem to favour the idea that naïve newborns have a preference for the causal sequence (i.e. the Launching Effect) over the non-causal interaction between objects. Nevertheless, results could be due to a preference for the intrinsic spatio-temporal features of the Launching Event rather than to a preference for the Causality per se. In fact, the Non-Causal Control stimulus differed from the Launching one for two main features: the absence of contact between the discs involved in the animation and the spatial discontinuity between the motion of disc A and B. Moreover disc B, which moved first, was also nearest to the fixation point (in fact both animations were presented to the newborn with discs moving in a convergent manner, i.e. from the peripheral to the central visual field).
For such reasons a Exp. 2 was conducted, in which newborns’ spontaneous preferences for a Launching Stimulus vs a Delay Stimulus were tested.
The Delay video animation was identical to the Launching one except for the presence of a 1 second-delay between the time of contact and the motion of B (such a delay is known to abolish any impression of physical causality in adults). Delay and Launching stimuli were selected as they were comparable as regards both their contact between disc A and B, and the spatial continuity of their motion. Moreover, the first disc to move was in both cases the farthest away from the fixation point. Obviously, the animations employed in this experiment differed from one another in the features necessary to obtain a causal vs a non-causal stimulus.
Data from this second experiment confirmed the newborns’ preference to look longer at the Launching animation, as previously shown in Exp. 1. Therefore, the results of Exp. 2 favour the idea that naïve newborns show a preference for a causal stimulus (i.e. the Launching Effect).
Such pattern of results, moreover, could not be due to a preference for the spatio-temporal features of the Launching animation rather than for its physical causality. In fact, in Exp. 3 newborns were presented with a “90° Launching Stimulus” and a “90° Delay Stimulus”, which were identical respectively to the Launching and the Delay Stimulus used in Exp. 2, except for a 90° deviation in the path travelled by disc B. In fact, in the stimuli employed in Exp. 3, disc B moved at the same speed as A, but along a vertical path, at a deviation of 90° from the trajectory of A. Such a deviation in trajectory is known to abolish any impression of physical causality in adult subjects (Michotte, 1963). In both the “90° Launching Stimulus” and the “90° Delay Stimulus”, therefore, any physical causality between the movements of the two discs was disrupted, whereas the distances covered by the discs and their velocities were respectively identical to those of the Launching Stimulus and of the Delay Stimulus used in Exp. 2. Data from this experiment, however, showed a preference for the “90° Delay Stimulus”.
Overall, the results showed a spontaneous preference in newborn babies for a causal (i.e. Launching) stimulus (Exp. 1 and 2). A stimulus with the same spatio-temporal features of the Launching Effect but lacking physical causality (Exp. 3) did not trigger any preference in newborn babies. It seems, therefore, that sensitivity to physical causality could be present from birth in our species.
Sensitivity to self-propelled motion as a cue of animacy in the domestic chicks
Self-produced motion provides one of the most powerful cues about what makes an object “animate”, i.e. a type of object distinct from one that can be put into motion only as a result of physical contact (Aristotle, Physics; New, Cosmides and Tooby, 2007). Developmental studies have shown that at a young age infants know that stationary objects start to move if, and only if, they are contacted by another moving object unless provided with an inner mechanism that permits self-produced motion (Luo and Baillargeon, 2005; Luo, Kaufman and Baillargeon, 2009). Current research, however, distinguishes between representations of animacy (entities that are capable of self-directed motion and of taking on the role of causal agent) and representations of intentional agency (entities with goals, attentional states, capable of perception and mental states like beliefs and desires). It is now recognized that self-propulsion is not a sufficient cue for agency detection (Csibra, 2008), whereas its role in pure animacy detection has not been yet investigated specifically.
In this thesis I was concerned only with self-produced motion as a pure animacy cue (i.e., with causal-agency and the presence of an internal force of action; Leslie and Keeble, 1987).
From previous research in non-human primates, moreover, it remains unclear as to what role self-propelled motion play in forming an expectation about an object’s potential capacity to change its spatial location (Hauser, 1998). This may also be confounded by the animals’ past experiences.
In this research I employed a methodology and a model species which allowed to circumvent this potential drawback. The newly-hatched domestic chicken was used as animal model since it is a precocial species which both allows for the rigorous control of sensory experiences, and for taking advantage of the phenomenon of filial imprinting (i.e., a learning process by which the young of some precocial species learn the characteristics of a potential social partner when exposed to it for a short time soon after hatching; Horn, 2004).
The aims of my research was to address two issues: First, does the basic distinction between inert and self-propelled objects also hold true in non-human animal species? Second, does such a distinction emerge as a result of experience or is it rather part of a natural predisposition?
All subjects came from eggs incubated and hatched in total darkness under controlled conditions, to prevent any visual experience. The same procedure was employed in all the 4 experiments. On their first day of life chicks were exposed to a computer-presented animation sequence picturing two oval-shaped objects of different colour to which motion could be attributed to either a causal agentive role (i.e., the object appeared as self-propelled) or a receptive role (i.e., the object appeared as moved by an external force). After exposure, chicks were tested for their spontaneous preference between the two objects.
In Exp. 1, chicks saw the two objects performing the classical example of Michotte’s perceived physical causality (i.e. the Launching Effect, described above; Michotte, 1963), in which people perceive object A as being a “self-propelled causal-agent” launching object B and causing its movement. When tested for their preferences for objects A and B we found that chicks showed a clear preference for object A, the self-propelled object playing the causal-agentive role during the exposure phase.
To check whether the perceived causality was crucial for the results obtained in Exp. 1, in Exp. 2 the order of the displacements was swapped temporally: thus object B moved first and object A started its movement only after object B had stopped. In this animation sequence any physical causality between the movements of the two objects was disrupted (no contact between A and B), whereas distances travelled and perceptual features of the two objects were identical to those of the launching effect. Both objects would thus appear to be self-propelled. At test, no significant preference was shown by chicks for either object.
Results of Exp. 1 could not, therefore, be due to a preference for the stimulus that moved first in the animation, since no preference for stimulus B (which moved first) was apparent in Exp. 2. However, given that in Exp. 2 any physical contact was removed, we wondered whether chicks’ preferences could be accounted for in terms of which object applied physical contact over the other object, which perhaps may have acted as a cue of “causal agency” in Exp. 1. To determine this, in Exp. 3 chicks were imprinted onto a Non-Causal Delay Animation. The stimulus sequence was identical to the Launching Effect used in Exp. 1 except for the presence of a 3 second-delay between the time of contact and the motion of B (as described above, in human subjects the presence of a delay is known to abolish any impression of physical causality; Michotte, 1963; Schlottmann et al., 2006): object B appeared in this case as being self-propelled, as was object A. Using those kind of stimuli at test, chicks did not exhibit any preference for either stimulus.
It remained unclear, however, whether the results of Exp. 1 were due to a preference for the self-propelled stimulus or to a preference for the object which was the “cause” of the motion sequence. To determine this, in Exp. 4 chicks were exposed to a video animation identical to the Launching Effect used in Exp. 1 except for the presence of two opaque screens, one of which occluded the object at the beginning and one at the end of the motion sequence. No cues were available about the self/not-self propelled nature of object A, although it continued to be perceivable as the cause of motion of object B. At test, chicks did not show any significant preference for either object.
The results of the experiments showed that only when one of the two objects appeared as being self-propelled and the other did not, did a preference emerge, as a choice for the self-propelled stimulus (Exp. 1). Physical contact which was not accompanied by physical causation (when both objects appeared as being self-propelled; Exp. 3), or physical causation without any cue about the nature (self/not-self propelled) of the motion of “the causal object” (Exp. 4), sufficed to abolish any preference.
Overall, the results thus demonstrate that newly-hatched chicks show an innate sensitivity to differentiate and prefer a self-propelled causal-agent as a target for imprinting. This may be sufficient to adaptively constrain the early commitment of a highly precocial animal as to what to imprint on.
Findings from this thesis, therefore, are compatible with the idea that many vertebrate species, including humans, have a primitive bias to attend toward, or preferentially process, sensory information about other living entities, both in terms of causal relations between them and in terms of animacy attributions.La capacità di identificare gli esseri animati e di cogliere rapporti causali tra eventi è probabilmente un'abilità fondamentale per la sopravvivenza delle diverse specie animali. É ben nota, al riguardo, la sorprendente capacità dell’essere umano di attribuire “animacy” (i.e., la caratteristica di possedere movimento auto-indotto e di poter agire come agente causale) e rapporti causali ad oggetti in movimento esclusivamente sulla base delle caratteristiche di tale movimento (Heider e Simmel, 1944; Michotte, 1963; Schlottmann, Ray, Mitchell, e Demetriou, 2006). Non si sa ancora nulla, tuttavia, riguardo all’origine di queste capacità, le quali potrebbero essere implicite o il prodotto di alcuni processi di apprendimento. Un’ulteriore fonte di dibattito, inoltre, riguarda il fatto che tali abilità possano essere presenti anche in specie animali diverse dalla nostra.
Per queste ragioni lo scopo di questa tesi è stato di investigare la sensibilità alla causalità fisica in un’ottica comparativa,
Animal visual perception
No full textPerception processes can be investigated at the physical (concerning the
stimulation from the environment to the receptors), physiological (the processes
taking place in the neural system), and psychological (the ‘sense’ of perception, the
outcome produced by the physical stimulation and the physiological processes)
level. The present paper focuses on visual perception, mainly from a psychological
level of investigation, and revises comparative literature, highlighting both
similarities and differences in the visual structures and functions in different
animal classes. For this purpose, the structure of the current eyes is described in a
comparative perspective, as well as perceptual organization and object recognition
processes, color perception, three-dimensional structuring of the image, and
motion perception. Finally, the literature about comparative susceptibility to
various visual illusions will be discussed, as illusory perception has been revealed
to be a most useful tool to unveil the perceptual algorithms shared by the different
species. In spite of major differences between animal species in the structures
in charge of perception and in the adaptations to specific ecological niches,
experimental data presented here will lead to the conclusion that a number of basic perceptual principles of organization and functioning are shared between species
Encuentros con Elena Poniatowska
No full textThe author analyzes testimonial literature from the perspective of female literature through his meeting with Elena Poniatowska. An analysis of reality vs. Fiction in Elena, Jesusa and Tinisima.El autor analiza, desde su encuentro con Elena Poniatowska, la vertiente de la literatura testimonial como literatura de mujeres. Un análisis interior de la relación entre realidad y ficción, entre Elena, Jesusa o Tinísima
Bio-bibliografía de y sobre Elena Poniatowska Amor
No full textThe objective of this article is to collect and present: I. the chronology of the life and work of Elena Poniatowska; II. the complete works (as principal and secondary author), and III. the bibliography on the author (books, chapters, and articles).El objetivo de este artículo es reunir y presentar: I. los datos cronológicos fundamentales de la vida y la obra de Elena Poniatowska; II. El compendio de sus obras (como autora principal y como secundaria); y III. la bibliografía sobre la escritora (libros, capítulos de libros y artículos)
El Tlacuache Núm. 698 (2015). 698 Año 13 (2015) noviembre. El Tlacuache
No full textLa mujer vista por cronistas en tiempos novohispanos por Laura Elena Hinojosa. - El Códice Mauricio de la Arena forma parte de Los códices de Tlaquiltenango por Laura Elena Hinojosa
Encounters with Elena Poniatowska
No full textEl autor analiza, desde su encuentro con Elena Poniatowska, la vertiente de la literatura testimonial como literatura de mujeres. Un análisis interior de la relación entre realidad y ficción, entre Elena, Jesusa o Tinísima.The author analyzes testimonial literature from the perspective of female literature through his meeting with Elena Poniatowska. An analysis of reality vs. Fiction in Elena, Jesusa and Tinisima
Was There a Quiet Revolution? Belarus After the 2006 Presidential Election
No full textThe 2006 presidential election in Belarus mobilized a large cross-section of society to protest against the Lukashenko regime. Although unprecedented, the mass mobilization was short-lived, failing to develop into another kind of coloured revolution in the region. The key to our understanding of the endurance of Lukashenko's regime seems to lie in its internal environment, and notably, in the seemingly contradictory feature of the Belarusian electorate. Not only do they fully identify with the president, thus effectively legitimizing his politics and policies; they also do so knowingly, through their strategic learning of how to survive and even thrive under Lukashenko's regime. This type of learning, however, may not necessarily lead to a critical reflection of the regime's malpractice, and thus is unlikely to challenge its foundations
Symmetry perception by poultry chicks and its implications for three-dimensional object recognition
No full textBilateral symmetry is visually salient to diverse animals including birds, but whereas experimental studies
typically use bilaterally symmetrical two-dimensional patterns that are viewed approximately frontoparallel;
in nature, animals observe three-dimensional objects from all angles. Many animals and plant
structures have a plane of bilateral symmetry. Here, we first (experiment I) give evidence that young poultry
chicks readily generalize bilateral symmetry as a feature of two-dimensional patterns in fronto-parallel
view. We then test the ability of chicks to recognize symmetry in images that would be produced by the
transformed view produced by a 408 horizontal combined with a 208 vertical rotation of a pattern on a
spherical surface. Experiment II gives evidence that chicks trained to distinguish symmetrical from asymmetrical
patterns treat rotated views of symmetrical ‘objects’ as symmetrical. Experiment III gives
evidence that chicks trained to discriminate rotated views of symmetrical ‘objects’ from asymmetrical
patterns generalize to novel symmetrical objects either in fronto-parallel or rotated view. These findings
emphasize the importance of bilateral symmetry for three-dimensional object recognition and raise questions about the underlying mechanisms of symmetry perception
From trans-disciplinary to "undisciplined" design learning: educating through/to disruption
No full textThe paper is fruit of a coordinated work, however the author of paragraphs 1 and 4 is Flaviano Celaschi, the author of paragraph 2 is Elena Formia and the author of paragraphs 3 and 5 is Eleonora Lup
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