When infants were allowed to fixate their own mother's face under various degrees of completeness, all showed differential fixation. A face without both eyes was fixated significantly less frequently than were the eyes only with or without other facial features and was also associated with a negative reaction of actively refusing to look. A full or complete face, however, was not fixated any more frequently than an incomplete which contained eyes. In another study, infants were allowed to fixate two television monitors on which were simultaneously presented filmed versions of a strange female face under various degrees of completeness. In spite of decided positional preferences, the results of the two studies correlated significantly, which indicates that infants responded to a filmed version of a face as face-like. It was therefore suggested that the human face as a visual stimulus can be conceived to be built up in the manner of a heterogeneous summation effect organized around a privileged feature, namely, one eye. The literature on imprinting was reviewed and the distinction between the minimally sufficient and the optimal conditions was drawn. Moreover, different types of imprinting were argued for. Then the development of attachment in the human infant, with particular reference to perception of the human face, was compared with imprinted recognition of and response to visual stimuli in birds, and it was pointed out that by 4 to 6 months, most infants evidence behaviour which indicates an internalized face schema.

Perceptual decision making refers to the process of making a choice among a series of options based on sensory information. Several studies have used visual stimuli to gain an understanding of the processes involved in encoding sensory information and its decoding, leading to a perceptual decision. One popular visual modality for studying these questions is motion and the ability to discriminate between axes of motion. Several mathematical models describing the processes of perceptual decision making have been proposed – many of them are based on data from electrophysiological experiments on macaque monkeys. By directly recording neuronal activity while monkeys were presented with different visual stimuli and making categorical choices about the perceived direction of motion, scientists have been able to study how decisions are made when enough perceptual evidence is accumulated to reach a threshold. A particularly interesting aspect of perceptual decision making is that it allows the study of situations in which the choice deviates from the physical features characterising the stimulus (e.g., a leftward motion is presented but the subject reports perceiving a rightward motion). A type of such perceptual bias is called reference repulsion: a systematic bias away from a reference when estimating the direction of motion of a stimulus. Several possible explanations of this phenomenon have been proposed: incorrect encoding of sensory information, influence of prior knowledge about the world, response-related factors such as expectations, rewards, and response history. The aim of this thesis was to shed light on when in the sequence of decision making such perceptual biases arise, as well as further address both sensory and higher-order factors that influence perceptual decisions of visual stimuli. We combined a series of psychophysical, eye-tracking, and neuroimaging studies, together with computational modelling approaches, to selectively look at the effect of: sensory information available during decision making, task-related sensory information processing, response modality, and also look for specific mechanisms involved in processing highly similar/dissimilar stimuli. The findings presented in this thesis show that perceptual biases in estimates of motion direction arise at a later stage than at the encoding of sensory representation, as previously thought. In particular, we show that information present at the time of the response is fundamental for the bias to emerge: the presence of a reference while estimating direction of motion results in reference repulsion, but this effect is not there when the same estimate is given in the absence of a reference. Moreover, the information given by the reference at the time of response – when subjects report the perceived motion, rather than at the time of stimulus presentation – plays a crucial role in the observed perceptual bias. These findings were used to develop a mathematical model able to describe the phenomena observed, as well as making a series of testable predictions. For example, the model could be used in future work to predict responses when more than one reference is present, when order of presentation of target and reference is inverted, and so on. By manipulating the modality with which subjects estimated the direction of motion of the stimuli they were presented with, it was also possible to show that a perceptual bias is observed for manual reproduction of the perceived direction, but not when the response is given by a saccadic eye movement. Finally, by looking at the brain activity recorded when performing a coarse / fine discrimination task in a functional magnetic resonance imaging (fMRI) study, we aimed at distinguishing between activity patterns encoding highly dissimilar / similar stimuli. For these analyses, we used both conventional, univariate analysis techniques, as well as a more advanced and relatively more recent multivariate approaches to the data. First, the retinotopic mapping of areas in early visual cortex and area MT was obtained through phase-encoded methods. Second, a version of the Generalised Linear Model was applied to the data measured while subjects were performing a fine / coarse discrimination task. This allowed to ensure the adequacy of tasks and stimuli used in the imaging study. I also applied the population Receptive Field methodology to fit a more explicit, physiologically relevant model of visual responses to the voxel-wise fMRI time series. Third, given that the spatial scale of the question we addressed in this study required aggregating sub-voxel differences in the fMRI responses during a fine versus coarse visual motion discrimination task, we employed a multivariate approach. This consisted in implementing a forward encoding model aimed at reducing the number of dimensions from several hundreds (given by the number of voxels) to a much smaller set of hypothetical channels. By considering the responses in these channels as a weighted combination from many hundred voxels we re-cast the activity patterns in a physiologically relevant space to predict responses to arbitrary visual motion directions. While there were very interesting aspects to the results from these imaging experiments, the analysis was inconclusive on any task-related shifts in stimulus encoding. Possible explanations, together with alternative paradigms that can be used in future to further address this question are discussed.

We can distinguish different forms of attention, for example paying attention to what we are thinking about, paying attention to what we hear, and paying attention to what we see or otherwise visually experience. This thesis is concerned with the form of attention paid to what we visually experience – visual attention. A natural way to think of visual attention is as sufficient for visual awareness: visually attending to an object is sufficient for being visually aware of it. (Plausibly, the relationship is closer. Visual attention is a way of being visually aware.) But we shouldn’t think of visual attention as necessary for visual awareness: we can be visually aware of objects that we are not visually attending to. In this thesis I provide a novel defence of the pre-theoretical conception of visual attention as sufficient, but not necessary, for visual awareness. Some psychologists have interpreted evidence, in particular from experiments involving subjects with blindsight, as proof that visual attention to an object is possible in the absence of any visual awareness of it. I argue we should not think of these results as proving that attention is not sufficient for awareness, but instead see them as motivation for a distinctively philosophical inquiry into the role of visual attention. I examine different explanations of the significance of visual attention for thought and action, ending with my own. Other psychologists have claimed, on the basis of experimental data, that visual attention is necessary for visual awareness. I argue this is inconsistent with the phenomenology of visual experience, and with other experimental data. I conclude that visual attention is sufficient but not necessary for visual awareness.

In this thesis I present a series of experiments that aimed to examine the effect of experience on the subsequent discriminability of similar stimuli. It has oft been observed that preexposure to stimuli enhances the rate at which a discrimination with similar stimuli will progress, or will reduce the amount of generalisation that occurs to similar stimuli following training. In animals, this effect has typically been studied using the conditioned taste aversion paradigm. Here, I describe a novel experimental method whereby animals learn to discriminate between textured stimuli, and do so differentially based on their previous experience with textures.

It is mostly agreed that in order to identify a visually presented word, both the identity and the position of it's constitute letters must be encoded. However, currently most models of word recognition only start after the processes involved in letter encoding has been completed: the so called “visual word form” level. These models concentrate on the process involved in the encoding of the letter position, giving several different solutions to the encoding problem. The problem here is not necessarily that there are different solutions but that each solution is as good at modelling the current data as the next. Thus the solution to disambiguating between them may lie in a better understanding of the sublexical processes involved. Although this seems a logical step it is surprising that very little research has been carried out regarding these processes. The aim of this current PhD project is to address some of the issues involved with investigating sublexical processes, and to start a systematic investigation of several early perceptual processes that may modulate visual word recognition.

This thesis is a defense of the Content View on perceptual experience, of the idea that our perceptual experiences represent the world as being a certain way and so have representational content. Three main issues are addressed in this work. Firstly, I try to show that the Content View fits very well both with the logical behaviour of ordinary ascriptions of seeing-episodes and related experiential episodes, and with our pretheoretical intuitions about what perceiving and experiencing ultimately are: that preliminary analysis speaks for the prima facie plausibility of such a view. Secondly, I put forward a detailed account of perceptual episodes in semantic terms, by articulating and arguing for a specific version of the Content View. I provide arguments for the following theses: Perceptual content is two-layered so it involves an iconic level and a discrete or proto-propositional level (which roughly maps the seeing-as ascriptions in ordinary practices). Perceptual content is singular and object-dependent or de re, so it includes environmental objects as its semantic constituents. The phenomenal character of perceptual experience is co-determined by the represented properties together with the Mode (ex. Visual Mode), but not by the perceived objects: that is what I call an impure representationalism. Perceptual content is 'Russellian': it consists of worldly objects, properties and relations. Both perceptual content and phenomenal character are 'wide' or determined by environmental factors, thus there is no Fregean, narrow perceptual content. Thirdly, I show that such a version of the Content View can cope with the objections which are typically moved against the Content View as such by the advocates of (anti-intentionalist versions of) disjunctivism. I myself put forward a moderately disjunctivist version of the Content View, according to which perceptual relations (illusory or veridical) must be told apart from hallucinations as mental states of a different kind. Such a disjunctivism is 'moderate' insofar as it allows genuinely relational perceptual experiences and hallucinations to share a positive phenomenal character, contrary to what Radical Disjunctivism cum Naïve Realism holds. Showing that the Content View vindicates our pre-theoretical intuitions and does justice of our ordinary ascriptive practices, articulating a detailed and argued version of the Content View, and showing that such a version is not vulnerable to the standard objections recently moved to the Content View by the disjunctive part, all that can be considered as a big, multifaceted Argument for the Content View.

Precognition can be defined as an anomalous correlation between current cognitive activity and a future event. Using behavioural and physiological measures, a number of previous studies have reported evidence for unconscious precognition during a variety of task conditions. The current thesis presents five experiments that were designed to test for unconscious precognition in the visual attention system while participants were engaged in a short term visual memory task. Each trial consisted of a study and test phase. In the study phase, participants were required to memorise an array of four stimuli while their eye movements were recorded. After a brief retention interval, a probe stimulus was presented for a yes/no recognition test. Two conditions were employed and were randomly determined. In the old condition, the probe was a stimulus viewed during study, termed the target. In the new condition, the probe was a novel stimulus. Experiments tested for the presence of precognition by examining whether there was a difference in the degree to which visual attention was allocated to items during the study phase of old and new trials. Two further studies were also carried out involving simulations that aimed to establish the extent to which a previously described artefact, termed the expectation bias, may impact on the results. Experiment 1 suggested that participants spent more time attending to target stimuli in old compared to new trials, a result that appeared to provide evidence for precognition. However, the data was considered unreliable due to inadequate randomisation. An exact replication of Experiment 1 was carried out in Experiment 2 with adequate randomisation, but failed to find evidence for precognition. Experiment 3A was a further attempt to replicate the preliminary results of Experiment 1 using more extensive randomisation procedures while Experiment 3B explored the potential role of the probe stimulus in generating a precognitive effect. However, no support for the precognitive hypothesis was found in either experiment. A fully balanced design was employed in Experiment 4 in order to control for potential confounds such as position and saliency effects. The results supported the precognitive hypothesis and suggested that less attention was allocated to targets in the old condition. An exploratory analysis also examined the relationship between several standardised stimulus variables and the apparent precognitive effect observed in Experiment 4. The results revealed a suggestive relationship between the size of the effect and item ratings of familiarity and visual complexity. Simulations of an expectation bias in Experiments 5A and 5B together with post-hoc examination of the data from the current series of experiments suggest that this artefact is not a plausible explanation for the observed effects. The thesis ends with a discussion of several methodological issues that may impact on both the interpretation of positive results and the conclusions that may be reached from this body of data as a whole. Finally, suggestions for further work are made.

This thesis is concerned with the perception of time in music with emphasis on tempo, emotion and time perception in music. Three studies were conducted to assess whether listeners were able to make consistent judgements about tempo that varied from piece to piece. Listeners heard short extracts of Scottish music played at a range of tempi and were asked to make a two alternative forced choice of 'too fast' or 'too slow' for each extract. The responses for each study were plotted as proportion too fast responses as a function of tempo for each piece, and cumulative normal curves were fitted to each data set. The point where these curves cross 0.5 is the tempo at which the music sounds right to the listeners, referred to as the optimal tempo. The results from each study show that listeners are capable of making consistent tempo judgements and that the optimal tempo varies across extracts. The results also revealed that rhythm plays a role, but not the only role in making temporal judgements. In the previous studies, it is possible that listeners might be using an average tempo from previously heard extracts to make every subsequent response. We wanted to assess this by presenting a single stimulus per participant and therefore remove any effects of the context on participant's responses. Using this technique we shall show that listeners can make 'too fast' and 'too slow' responses that are independent of previously heard extracts. In addition the data reveal similar results to those found in the first experimental chapter. The 3rd chapter deals with the effect of changes in the tempo of music on the perception of happy and sadness. Listeners heard short extracts of music that varied in tempo and were asked to make a 2AFC of happy or sad for each extract. Separate psychometric functions were obtained for each extract of music, and the points where these crossed 83% and 17% happy were calculated, and treated as happy tempo and sad tempo respectively. The results show that most extracts can be perceived as both happy and sad just by varying the tempo. However, the tempo at which extracts become happy or sad varies widely from extract to extract. We show that the sad and happy tempi are related to the size of the intervals (pitch changes) in the extract. In considering what might be involved in the perception of time in music we wanted to assess what effect small changes to a stimulus would have on perceived duration. We presented 2 auditory stimuli and show that the perceived duration of the test stimulus with a change in pitch increased as the size of the pitch change increased. The results are explained in terms of event strength where strong events cause perceived duration to increase whilst weak events are perceived to be shorter by comparison.

Includes errata / Bibliography: leaves 242-254 / xiv, 254 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Psychology, 1985

I argue in this thesis that qualitative duration (viewed in opposition to the construct of quantitative clock-time) can be experienced through performance encounters that challenge smooth consumption. In a socially accelerated culture, where to do more in less time is the measure of a productive life, one’s connection with the ‘real’ time of duration is diminished. To challenge this premise, I have used an autoethnographic approach to explore an experience of duration conceived via the work of French philosopher Henri Bergson, who posits that “pure duration [is that which] excludes all idea of juxtaposition, reciprocal externality, and extension” (Bergson, 1903/1999, p. 26). In other words, Bergson asserts that duration defies quantitative measurement. I argue that the Bergsonian experience of duration offers a pause from social acceleration and effects a transformation for the spectator in the form of peak-experience, flow, and communitas.