This research deals with some perceptual aspects of shape and colour vision, and specifically with the relation between the widespread phenomenon of amodality in vision and the multifarious characteristics of colour appearances. The study is divided into a theoretical and an experimental part, and the rationale of the two experiments is discussed within the systematic framework illustrated in Chapter 1 and Chapter 2, respectively on the topics of colour and amodality. The third chapter describes an experiment carried out in order to study the effects of colour in dimensional phenomena. The results show that colour has an effect on amodal completion, and particularly regarding dark/light colours and harmonic and disharmonic configurations. The fourth chapter describes an experiment carried out in order to test the existence of a perceived natural relationship between shape and colour using non-geometrical figures. The aim of this study was to verify whether there is a natural relation between colours and natural shapes, and which elements or parts of the shapes – like orientation, type of shape, margins, texture or dimensionality – might be responsible for that relation and explain it. The results confirmed the initial hypothesis. Overall, one of the best achievements of the research reported, has been its demonstration of the feasibility of the phenomenological methods, complementary to psychophysical methods in the scientific analysis of visual perception.

In the last decade, a consistent body of research has shown that the correct identification of task-relevant items can cause a transitory increase in human perceptual sensitivity. In the present work I report evidence of short- and long-term changes in perceptual processing triggered by the recognition of visual targets. This collection of studies suggests that targets recognition may trigger internal signals of reinforcement which, in turn, would foster cortical plasticity. Interestingly, such endogenous signals seem to be modulated by the presence of external reward and by intrinsic aspects of task performance.

In everyday life, our body gets in contact with multiple tactile stimuli from the outside world. How our somatosensory system identifies and localises these multiple stimuli entering in contact with our body surface, is the general framework to which the researches of the present thesis belong. Tactile stimuli on our body can be spatially coded and represented by using multiple reference frames. Touch is initially encoded into a sensory-space within primary somatosensory map and then further stages of processing can represent the location of tactile event with respect to the overall body structure (body-space) or to the outside world (external-space). In the present thesis we report first a series of behavioural experiments aimed at investigating which spatial reference frame is adopted in a special context of sensory stimulation, namely the double simultaneous stimulation (DSS). Then, we used functional magnetic resonance (fMRI) as a tool for delineating the neural bases of the cognitive processes sub-serving the elaboration and representation of concurrent stimuli for conscious tactile perception. In a first behavioural study using the tactile DSS paradigm, we defined the spatial coding used by observers when tactile stimuli are delivered with different fingers combinations (i.e., within vs. between hands) and hand postures (i.e., hands palm-down vs. palm-up). In a second behavioural work we tested the influence of different visual modulations (e.g., seeing body parts or objects) and visual-proprioceptive conflict (e.g., seeing body parts in a different position with respect to one adopted by the participant) on the spatial representation of touch. Furthermore, we investigated the effect of changes to the visual structural morphology of a body part on the spatial representation of touch. Finally, using a fMRI adaptation paradigm for touches at the fingers, we aimed to define the neural bases of tactile perception in a repeated stimulations context. In particular, we assessed the mutual interaction between tactile stimuli located at body parts that are clearly distinct in terms of the body-space (e.g., left and right index fingers), but proximal in terms of neural representations (due to some bilateral responses of the somatosensory cortices).

Reward cues acquire distinctive incentive properties from their association with motivationally significant outcomes. These incentive properties are manifest in an augmented salience that provides reward cues with the capacity to attract attention, also in contexts where pursuing the reward is not relevant. I will first examine the unresolved debate concerning the learning parameters that define the cue-reward association and eventually modulate attention. Specifically, whether the cue attentional salience is governed by reward expectancy or uncertainty. I will then study another incentive property of reward cues, that is the ability to strengthen the performance of a separately learned instrumental action exerted to obtain an outcome, a phenomenon known as Pavlovian-Instrumental transfer (PIT). Since the motivational value of reward is altered when reward is devalued, an interesting question is whether the incentive properties of reward cues change accordingly, both in the attentional and in the operant domain. Therefore, I will investigate the effects of motivational shifts on the incentive properties of reward cues, by means of reward devaluation. In the context of the ability of a cue attentional salience to update in accordance with the altered outcome value, I will further analyze the influence of incentive learning (i.e. the possibility to re-associate the cue with the devalued outcome). The procedures adopted through the experiments share two main phases: a learning phase in which human thirsty participants learned cue-beverage reward associations involving different contingencies, and a test phase in which no reward was delivered. During the learning phase, participants accumulated the beverage reward that acted as an incentive, since it was not consumed through this phase. This allowed a controlled devaluation procedure by consummatory satiation (i.e. a motivational shift) that was administered at different moments during the experiments depending of the hypothesis at test. Results showed that the cues that better predicted the reward during learning were the stimuli preferentially attended at test, and the stimuli that invigorated more the instrumental action for the outcome. These incentive attributes persisted despite reward devaluation: the attentional bias and the PIT effect emerged unaltered after participants quenched their thirst. Reward cues persisted in capturing attention after reward devaluation even when participants were given the chance for incentive learning by means of an additional learning phase. Taken together, the evidence that emerged indicates that the incentive properties of reward cues, once acquired, can surprisingly and irrationally outlast reward devaluation and can resist incentive learning, suggesting that some incentive properties of the cue can become independent from those of the reward. These results may provide important implications for the understanding of the psychological mechanisms underlying different types of addiction.

Despite the large amount of work that has been conducted since Donald’s Hebb work and described in his famous dissertation “The Organization of Behavior” (Hebb, 1949), understanding the experience-dependent mechanisms of plasticity within the primary visual cortex (V1) remains a major priority. Although plasticity effects are strongest during the critical period (early development), studies on cortical plasticity from the last two decades have clearly demonstrated that the human brain is plastic and amenable to changes throughout life. Perceptual Learning (PL) is one of the most commonly used procedure to promote visual improvement in neurotypicals and recovery of functions in a variety of disorders. However, a common feature to most of the training protocols is that they require long time and a high number of sessions to show effective improvement. Recently, non-invasive brain stimulation (NIBS) techniques, specifically transcranial random noise stimulation (tRNS) and anodal tDCS, have been used to modulate activity within the visual cortex to enhance perceptual learning. However, the mechanisms of action and the long-term effects on learning are still unknown. The questions this thesis work will address are the following: (1) can neuromodulatory techniques be used to boost visual perceptual learning in neurotypicals, which technique is the most effective and what are the long term effects on learning? (2) what are the potential underlying physiological mechanisms modulating cortical excitability of the visual cortex? and (3) contingent upon results from (1), can NIBS be used over early, peri-lesional visual areas during visual training to induce recovery of visuo-perceptual abilities in chronic partial cortical blindness (CB)? I used tRNS coupled with visuo-perceptual training protocols to promote fast and sustained perceptual learning in neurotypicals. I then provide evidence that tRNS can increase cortical excitability of the visual cortex, measured by priming early visual areas with tRNS, before measuring phosphene threshold with single pulse TMS. Lastly, I provide preliminary

Objects belonging to different categories elicit reliably different response patterns in human ventral temporal cortex, with the most prominent distinction being that between animate and inanimate objects. However, it remains unclear whether these categorical distinctions genuinely reflect object category or, alternatively, category-associated visual properties. To address this question, we designed a stimulus set in which animate and inanimate stimuli were carefully matched for shape. Different aspects of visual similarity of the stimuli were measured in three behavioral visual search tasks. We then conducted an fMRI study to test the hypothesis that animate-inanimate organization in VTC response patterns can be explained by visual properties of these categories. We found that it was not the case: although visual dissimilarity predicted neural dissimilarity across the visual cortex, we also found regions in which category information was present even after regressing out visual dissimilarity. We then conducted an MEG study to examine the time course of shape- and category-related information in the brain. Following the analysis approach used in the fMRI study, neural dissimilarity of MEG sensor patterns was modeled using regression analysis, where visual dissimilarity and categorical dissimilarity served as predictors of neural dissimilarity. The results show that visual object properties were strongly contributing to MEG sensor patterns. Surprisingly, when regressing out the contribution of visual properties, no residual category information was present in MEG response patterns. These results suggest that MEG sensor patterns evoked by visually presented objects predominantly reflect visual object properties. Taken together, these findings suggest that MEG is less sensitive to object category information that is independent of shape information.

Recent findings suggest that people with dyslexia experience difficulties with the learning of serial order information during the transition from short- to long-term memory. At the same time, models of short-term memory increasingly incorporate a distinction of order and item processing. This work aims to investigate whether serial order processing deficiencies in dyslexia can be traced back to a selective impairment of short-term memory for serial order, and whether this impairment also affects processing beyond the verbal domain. In three studies, dyslexic children in Italy, good and poor reading school children in Germany and a sample of adults in Belgium participated in 2 x 2 experiments in which short-term recognition performance for order and item information was assessed, using both verbal and nonverbal material. The findings indicate that, irrespective of the type of material, children and adult participants with dyslexia recalled the individual items with the same accuracy as the matched control group, whereas the ability to recognize the serial order in which those items were presented appeared to be affected in the dyslexic groups. This work concludes with the assumption that dyslexia is characterized by a selective impairment of serial order short-term memory and discusses the implications of these findings for current theoretical views on dyslexia and its associated dysfunctions.

Teaching and learning in a foreign language: the CLIL approach in Europe, in Italy, in Trentino. Monitoring a CLIL pilot programme at Primary school in Italy: Context Analysis and Curriculum Study. Arithmetic facts and language of acquisition effects in Primary school children: Experiment 1,2,3 and 4. Arithmetic facts in Primary school children:Does the language of acquisition really matter? Experiment 5 and 6.

Human occipitotemporal cortex (OTC) is organized into distinct areas that are selectively activated by the visual presentation of different categories, like faces (Kanwisher et al., 1997), bodies (Downing et al., 2001), tools (Chao et al., 1999), hands (Bracci et al., 2010), and places (Epstein et al., 1999). However, the precise role of these areas in processing their preferred stimulus category is still unclear. Moreover, the debate on how such brain organization originates is still unresolved. In order to investigate these issues, we focused on one of these selective areas: a region in left lateral-occipitotemporal cortex (lLOTC) that has been shown to be selective to both hands and tools and that is functionally connected to left intraparietal sulcus (IPS) and premotor cortex (PM), regions involved in action processing (Bracci et al., 2012). Although tools and hands are visually very different, they are both involved in object-directed actions. Thus, lLOTC might process both categories in order to efficiently communicate with IPS and PM. Alternatively, however, tool selectivity in lLOTC may simply reflect epiphenomenal association of tools with hands, for example related to mental imagery. Furthermore, the role of feedback projections between IPS and lLOTC in shaping tool selectivity in lLOTC has not yet been investigated. Using fMRI, we found that lLOTC was more strongly activated when participants processed action-related properties of tools (deciding on the typical hand action associated with a tool), as compared to when they processed contextual properties of tools (deciding on the typical location associated with a tool). Importantly, TMS over lLOTC led to a specific decrease in accuracy for action judgments but not for contextual judgments, supporting a causal role for lLOTC in processing tool actions. We investigated lLOTC-IPS connections by interleaving repetitive TMS with short fMRI scans. In a first experiment, we applied TMS over left IPS and found a decrease in BOLD signal in left IPS, confirming that TMS suppressed neural processing in the target area. Moreover, BOLD responses also decreased in left dorsal PM and right IPS, suggesting that these two areas receive projections from left IPS. However, no significant change was found in lLOTC, indicating that tool selectivity in lLOTC does not require feedback from IPS. In a second study, we stimulated lLOTC. In this study, however, no significant TMS-induced BOLD changes were found in the target region, possible reflecting insufficient statistical power. In conclusion, our results show that lLOTC is critical in processing action-related properties of tools, indicating that tool selectivity in this area reflects processes that are necessary for understanding tool actions. As a consequence, the finding that lLOTC is causally selective for both tools and hands, even if these two categories are visually very different, supports the hypothesis that the functional organization of OTC partly reflects non-visual organizational principles. Finally, the fact that we did not find significant back projections from IPS to lLOTC suggests that the role of lLOTC in processing tools does not arise as a consequence of activity in higher areas, but that lLOTC is relatively autonomous in processing action-related properties of tools.

In this thesis, I am going to address the issue of how both reward and punishment affect visual representation, by the use of a visual search paradigm performed in naturalistic scenes. More specifically, I am going to approach these two motivational forces by referring to their constituting dimensions, namely valence and salience. In fact, while being positioned in oppositely valenced space, these two outcomes share the burden of signaling stimuli with strong behavioral importance, coding therefore for motivational salience. After reviewing the main existing literature in this field (Chapter 1), I will describe a series of studies which examine how reward and punishment impact visual attention through the analysis of behavioral measures (Chapter 2) and fMRI activation (Chapter 3 and 4). The main idea resulting from these studies is that, in spite of what a rational approach to the problem would suggest, automatic visual attention does not process these two outcomes according to a salience, but rather through a valence pattern.