This thesis addresses a range of interdependent themes centred on how emotions are picked up from the body movements of actors engaged in natural communication. There were 4 main aims. The first considered the importance of the social context. The second was to further our understanding of the mechanisms responsible for the perception of affect from biological motion. The third considered how the skill to read affect from body movements develops in children. The final aim was to further elucidate what is known about affect. A corpus of point-light displays were created from the body movements of pairs of female and male actors engaged in interlocution whilst emoting. A MacReflex motion analysis system was used to record their movements. Observers viewed either the original and/or various permutations of the original displays and made judgements about the portrayed emotions. The results of the first set of experiments, which tested whether subjects could recognise the emotions and also explored the effects of inversion, were in line with previous findings which showed that emotions can be recognised from biological motion and that inversion impairs recognition. However, this latter effect varied, depending on the emotion shown. Of central importance, the following two experiments considered the social context of the displays. For most of the emotions tested, it was found that seeing a natural interaction made a statistically significant enhancement to how well many emotions were recognised. This finding highlights the need for natural stimuli and the need to consider emotions at a social, as well as an intrapersonal, level. The mechanisms were further investigated in the next set of experiments. It was shown that biological motion of affect is processed differently to biological motion of locomotion. The final investigation focused on how children develop this ability: Children as young as five are able to identify some of the emotions shown and by age nine development is almost at adult levels. In summary, the findings reported in this thesis show that the social context is important in emotion and future studies should incorporate the social context in the stimuli. They also lend support for a) categorical theories of emotion and b) the existence of distinct modules in the mind.

While previous work has identified the existence of people with extraordinary face recognition skills (so-called “super-recognisers”; SRs), the cognitive and perceptual underpinnings of the ability are unknown. This thesis addresses this issue, using behavioural and eye-movement measures. It also evaluates the methods used to identify SRs, their role in more applied national security settings, and ways of improving face recognition in typical perceivers. The first set of studies offers an in-depth cognitive and perceptual examination of six SRs using a case-series approach. This investigation revealed that while SRs are a heterogeneous group, they consistently show enhanced holistic processing. A second set of studies examined the eye-movements of SRs in a standard face memory task and a more ecologically valid free-viewing task. In both experiments SRs spent more time looking at the nose (i.e. the centre of faces) than typical perceivers, countering previous work that suggests the eye region is critical in facial identification. A subsequent study was aimed at establishing the UK-specific norms for dominant tests of face recognition and face perception, using a large sample of young British adults. Results suggested that females are better at face recognition than males, and that country-specific control norms are needed for these neuropsychological tests. A fourth set of studies looked at the performance of SRs on more applied face recognition tasks, replicating face matching and recognition scenarios. Results strongly suggested that some SRs are best-suited to particular tasks, and when identified correctly would make extremely valuable employees in national security settings. A final study examined if face matching and face recognition skills can be improved in typical perceivers via intranasal inhalation of the nonapeptide oxytocin, yet neither process was improved following this intervention. The theoretical and practical implications resulting from all these vi investigations are discussed, particularly in relation to our understanding of the typical face-processing system, and in making practical recommendations for the implementation of super recognition in national security settings.

The experiments presented in this thesis sought to establish combinatorial effects operating within novel semantic priming paradigms. These experiments demonstrate the combining of several pieces of semantic information (specifically, what certain items afford in terms of some form of interaction) from objects within simple visual scenes, and an account is offered based on the construction of representations from these presented items. These composite representations subsequently facilitate responses to target items, but it is only with a combination of items (e.g. a knife and a tyre) that is felicitous to a particular event (e.g. bursting) that priming to target items (e.g. a burst tyre) obtains. Priming is less evident when a combination of items is presented that does not allow the same event to occur (e.g. a ruler and a tyre). These combinatorial processes appear to occur in longer time windows than those of automatic visual processes such as gist abstraction, and the representations activated upon viewing these stimuli appear to be specific to the objects presented.

The aim of this thesis is to shed light on the Oppel-Kundt, vertical-horizontal and Helmholtz’s squares illusions. Eleven psychophysics experiments and one final fMRI study were conducted in order to inform current literature regarding these illusions. Experiments 1-5 investigated the effect of the number, size and position of vertical lines on the Oppel-Kundt illusion. Whereas five vertical lines allow for veridical size judgment of a horizontal line, a relatively constant and significant Oppel-Kundt 5% effect is observed with eight to twelve vertical lines. Evidence from these experiments also demonstrates that when one vertical line crosses a horizontal, ‘bisection’ decreases the perceived size of the horizontal by 7-13%. However, no reduction in the perceived size of the horizontal line in an inverted ‘T’ configuration is observed, challenging the ‘bisection’ component of the vertical-horizontal illusion as described by Mamassian & de Montalembert (2010). Experiments 6-7 showed that the increase in the perceived size of a horizontal line in an Oppel-Kundt figure can only be partly explained in terms of repulsion between adjacent lines. Specifically, whereas the size of the Oppel-Kundt illusion is 5%, displacement of adjacent lines can only account for 0.5%. Experiments 8-11 assess Mamassian and de Montalembert’ s (2010) simple model of the vertical-horizontal illusion and propose the new ABC model consisting of three components; anisotropy, abutting and bisection which were found to affect the perceived size of lines by +7%, +9% and -7% respectively. Finally, an fMRI study was carried out to investigate whether activity in V1 can be linked to perceptual experience. Results generated revealed a significant effect in V1 associated with physical differences between visual stimuli rather than perceived differences. We concluded that intrinsic processing in V1 is not responsible for inducing illusion-related activity and it is likely that feedback from other areas dominates results of other studies. The findings of this thesis have important implications on theories of visual illusions and processing of illusory-related percepts in the brain.

This thesis aimed to explore spatial memory in fish through a series of maze experiments (four experimental chapters in total). The first experimental sought to examine spatial memory strategy choice (place versus response) in four species of fish, namely goldfish (Qarassius auratus auratus), killifish (Nothobranchius guentheri), Siamese fighting fish (Betta splendens) and zebrafish (Danio rerio). Results suggested that the fourth species listed did not show a preference for either strategy, whereas the former three all chose to us a place strategy to solve the standard plus-maze task. Zebrafish are typically a shoaling species and, as such, chapters 3 and 4 explored the effect of shoaling on the spatial memory of this species. It was found that when completing the standard plus-maze task as a group, shoals of zebrafish preferred to employ a place strategy. Furthermore, however, it was also group that individual zebrafish that were trained within a shoal but completed the probe trail alone did not transfer spatial knowledge to their own navigation (i.e. individuals trained as members of shoals still did not show a preference for either a place or a response strategy when completing the probe trial alone). The final experimental chapter aimed to assess the effect of aging on two species of killifish (Nothobranchius guentheri and Fundulopanchax gardneri) through a set of longitudinal experiments and a between-groups design (one group of young fish and one group of aged fish), respectively. Results did not point towards an age-related decline in spatial memory capabilities in these fish, although these conclusions are rather tentative and further work is required to increase the sample size here. Overall, this thesis adds to and develops the existing body of research suggesting fish are an excellent comparative species for exploring spatial memory.

A great deal of previous research has demonstrated that face recognition is unreliable for unfamiliar faces and reliable for familiar faces. However, such findings typically came from tasks that used ‘cooperative’ images, where there was no deliberate attempt to alter apparent identity. In applied settings, images are often far more challenging in nature. For example multiple images of the same identity may appear to be different identities, due to either incidental changes in appearance (such as age or style related change, or differences in images capture) or deliberate changes (evading own identity through disguise). At the same time, images of different identities may look like the same person, due to either incidental changes (natural similarities in appearance), or deliberate changes (attempts to impersonate someone else, such as in the case of identity fraud). Thus, past studies may have underestimated the applied problem. In this thesis I examine face recognition performance for these challenging image scenarios and test whether the familiarity advantage extends to these situations. I found that face recognition was indeed even poorer for challenging images than previously found using cooperative images. Familiar viewers were still better than unfamiliar viewers, yet familiarity did not bring performance to ceiling level for challenging images as it had done in the cooperative tasks in the past. I investigated several ways of improving performance, including image manipulations, exploiting perceptual constancy, crowd analysis of identity judgments, and viewing by super-recognisers. This thesis provides interesting insights into theory regarding what it is that familiar viewers are learning when they are becoming familiar with a face. It also has important practical implications; both for improving performance in challenging situations and for understanding deliberate disguise.

People are often found to temporally overestimate the duration of emotionally salient stimuli relative to neutral stimuli. To date there has been no investigation into the behavioural consequences of such an effect or whether such an effect can be enhanced. Experiments 1, 2 and 3 investigated whether a behavioural advantage to temporally overestimating the duration of emotive stimuli exists. Reaction time facilitation was found following the display of an emotive stimulus which was more frequently temporally overestimated than a neutral stimulus. This provides support for the notion that temporal overestimation due to threat prepares one to act. However, such effects were not found in Experiment 1. Experiments 4 and 5 used multiple experimental manipulations to induce an enhanced temporal overestimation effect. Neither experiment provided evidence that one’s perception of time can be distorted to a greater amount than has been previously demonstrated. This is explained by the operation of an internal clock, such as scalar expectancy theory (SET) (Gibbon, Church, & Meck, 1984), operating at some maximum level. Finally Experiment 6 used electroencephalography to investigate the N1P2 complex in spider phobic and non-phobic individuals. The peak amplitude of the N1P2 complex was not modulated by the spider stimuli, however, the latency of the N1 component was found to be earlier when a spider stimulus was presented. It is suggested that the reaction time facilitation reported in Experiments 2 and 3 of this thesis may not be attributable to temporal overestimation per se, but instead is the result of a general cognitive speeding effect which also leads to temporal overestimation.

Cross-cultural studies have identified a distinct holistic-analytic pattern that observers employ in various cognitive and perceptual tasks. Recent face perception studies utilizing eye tracking methodologies have also revealed distinct Eastern and Western viewing patterns when recognizing identities and emotions. However, studies exploring genetic and cultural factors found that British born Chinese observers employed either Eastern or Western eye movement strategies, suggesting that a simple Eastern-Western distinction does not fully explain the diversity in observers’ eye movement strategies. Although Malaysia is an East Asian country, it is strongly multicultural and heavily influenced by Western culture. This thesis aimed to investigate Malaysian Chinese participants’ eye movement strategy and recognition abilities by requiring participants to perform static and dynamic face recognition, and emotion recognition tasks on African, East Asian, and Western Caucasian faces.

The identification of unfamiliar faces is known to be inferior to the recognition of faces with which we are familiar. This can lead to undesirable consequences such as misidentification. However, there is some evidence to suggest that a brief period of familiarisation can dramatically improve our ability to recognise an unfamiliar individual. Chapter 1 outlines the previous research that has aimed to understand the mechanisms of face processing, and to improve the recognition of unfamiliar faces. Three areas that require further investigation are identified and the experimental work reported in the three empirical chapters addresses these issues. Chapter 2 reports five experiments, using photographs of faces as stimuli, which examined whether a short training exposure promoting stimulus comparison can facilitate recognition of unfamiliar faces (c.f. Dwyer & Vladeanu, 2009). The results revealed that, contrary to expectation, any beneficial effects of comparison do not extend to improving discrimination between targets and nonexposed stimuli. The results of Chapter 2 required a return to the mechanisms of perceptual learning thought to underpin the comparison effect. Numerous attempts to unpack this process have relied on experiments that have examined the content, but not the location, of the unique features of a stimulus (e.g., Hall, 2003; Mitchell, Nash, & Hall, 2008; Mundy, Honey, & Dwyer, 2007). Chapter 3 used checkerboards as stimuli, manipulating the placement of the unique feature, as a way of breaking the perfect correlation between content and location and assess their relative contributions to perceptual learning. The findings indicated that discrimination between similar stimuli on the basis of exposure can be explained entirely by learning where to look, with no independent effect of learning about particular stimulus features. 11 Chapter 4 returned to the issue of potential methods to improve recognition, and examined the possibility that training using synthesised faces created from a single view and presented at multiple yaw rotations can aid face recognition (Liu, Chai, Shan, Honma, & Osada, 2009). The findings of three experiments; strengthen the claim that identifying an individual can be improved using multiple synthesised views generated from a single front view of a face, and suggest that this improvement may be affected by the quality of synthesised material. In summary, while the results reported within this thesis indicate that comparison between similar faces does not produce an effective way of supporting the recognition of unfamiliar faces, they do indicate that experience with a face and/or artificial faces may be a practical means of facilitating identification.

The ability to choose wisely is crucial for our survival. Yet, the received wisdom has been that humans choose irrationally and sub-optimally. This conclusion is largely based on studies in which participants are asked to make choices on the basis of explicit numerical information. Lately, our ability to make such high-level choices has been contrasted with our ability to make low-level (perceptual or perceptuo-motor) choices. Remarkably, we seem able to make near-optimal low-level choices. Taken at face value, the discrepancy gives rise to a perception-cognition gap. The gap implies, for example, that our ancestors were much better at choosing where to put their feet on a rocky ridge (a perceptuo-motor task), compared to choosing which prey to hunt (a cognitive task).The work reported herein probes this gap. There are many differences between literatures showing optimal and sub-optimal performance. The main approach taken here was to match low- and high-level tasks as closely as possible to eliminate such differences. When this is done one finds very little evidence for a perception-cognition gap. Moreover, once the standards of performance assessment of the respective literature are applied to data generated under such conditions it becomes apparent that the cause of the gap seems to lie in the standards themselves. When low-level standards are applied, human choice, whether low- or high-level, looks good. When high-level standards are applied, human choice, whether low- or high-level, looks rather poor. It is easy to see then, that applying high-level standards to high-level tasks, and low-level standards to low-level tasks, will give rise to a “gap”, with no or little actual difference in performance.