[Truncated abstract] Recent studies have provided evidence that face-coding mechanisms reference a norm or average face (Leopold, O`Toole, Vetter & Blanz, 2001; Rhodes & Jeffery, 2006). The central aim of this thesis was to establish whether distinct norms, and dissociable neural mechanisms code faces of different race and sex categories. Chapter 1 provides a brief introduction to norm based coding of faces, and reviews evidence for the existence of distinct norms for different races and sexes. Chapter 1 then introduces adaptation as a tool for investigating these ideas. Chapter 2 presents two adaptation studies that examined how faces of different races are coded. The aim of these studies was to determine whether dissociable neural mechanisms (or distinct face norms) code faces of different races. Chinese and Caucasian participants rated the normality of Caucasian and Chinese test faces, before and after adaptation to distorted faces of one race (e.g., 'contracted' Chinese faces; Experiment 1) or distorted faces of both races (e.g., 'contracted' Chinese faces and 'expanded' Caucasian faces; Experiment 2). Following adaptation to faces of one race, there were changes in perceived normality for faces of both races (i.e., perceptual aftereffects), indicating that common neural mechanisms code Chinese and Caucasian faces. However, aftereffects were significantly smaller in faces of the unadapted race suggesting some sensitivity to the race of faces. This sensitivity was also evident in Experiment 2. ... Some dissociability was also found in the coding of faces of different iv sexes. In Experiments 2 and 3, participants adapted to oppositely distorted faces of both sexes. Weak sex-selective aftereffects were found. Taken together, the findings suggest that male and female faces are coded by dissociable but not completely distinct neural populations. Chapter 4 examined whether the aftereffects reported for faces of different races or sexes reflected the adaptation of high-level neural mechanisms tuned to the social category information in faces, or earlier coding mechanisms tuned to simple physical differences between face groups. Chinese and Caucasian participants adapted to oppositely distorted face sets that were the same distance apart on a morph continua. The face sets were either from different race categories (e.g., contracted Chinese faces and expanded Caucasian faces), or from the same race category, (e.g., contracted Chinese faces and expanded caricatured Chinese faces). Larger opposite aftereffects were found when face sets were from different race categories, than when they were from the same race category suggesting that oppositely adapted neural mechanisms are tuned to social category differences rather than simple physical differences in faces. Together, these studies shed new light on how we code faces from different face categories. Specifically, the findings indicate that faces of different races and sexes are coded by both common and race- or sex-selective neural mechanisms. In addition, the findings are consistent with the possibility that race- and sex-selective norms and dimensions are used to code faces in face space. The implications of these findings and possible avenues for future research are discussed.

Recent studies have shown that there is a visual influence early in speech processing - visual speech enhances the ability to detect auditory speech in noise. However, identifying exactly how visual speech interacts with auditory processing at such an early stage has been challenging, because this so-called AV speech detection advantage is both highly related to a specific lower-order, signal-based, optic-acoustic relationship between the second formant amplitude and the area of the mouth (F2/Mouth-area), and mediated by higher-order, information-based factors. Previous investigations either have maximised or minimised information-based factors, or have minimised signal-based factors, in order to try to tease out the relative importance of these sources of the advantage, but they have not yet been successful in this endeavour. Maximising signal-based factors has not previously been explored. This avenue was explored in this thesis by manipulating speaking style, hyperarticulated speech was used to maximise signal-based factors, and hypoarticulated speech to minimise signal-based factors - to examine whether the AV speech detection advantage is modified by these means, and to provide a clearer idea of the primary source of visual influence in the AV detection advantage. Two sets of six studies were conducted. In the first set, three recorded speech styles, hyperarticulated, normal, and hypoarticulated, were extensively analysed in physical (optic and acoustic) and perceptual (visual and auditory) dimensions ahead of stimulus selection for the second set of studies. The analyses indicated that the three styles comprise distinctive categories on the Hyper-Hypo continuum of articulatory effort (Lindblom, 1990). Most relevantly, both optically and visually hyperarticulated speech was more informative, and hypoarticulated less informative, than normal speech with regard to signal-based movement factors. However, the F2/Mouth-area correlation was similarly strong for all speaking styles, thus allowing examination of signal-based, visual informativeness on AV speech detection with optic-acoustic association controlled. In the second set of studies, six Detection Experiments incorporating the three speaking styles were designed to examine whether, and if so why, more visually-informative (hyperarticulated) speech augmented, and less visually informative (hypoarticulated) speech attenuated, the AV detection advantage relative to normal speech, and to examine visual influence when auditory speech was absent. Detection Experiment 1 used a two-interval, two-alternative (first or second interval, 2I2AFC) detection task, and indicated that hyperarticulation provided an AV detection advantage greater than for normal and hypoarticulated speech, with less of an advantage for hypoarticulated than for normal speech. Detection Experiment 2 used a single-interval, yes-no detection task to assess responses in signal-absent independent of signal-present conditions as a means of addressing participants’ reports that speech was heard when it was not presented in the 2I2AFC task. Hyperarticulation resulted in an AV detection advantage, and for all speaking styles there was a consistent response bias to indicate speech was present in signal-absent conditions. To examine whether the AV detection advantage for hyperarticulation was due to visual, auditory or auditory-visual factors, Detection Experiments 3 and 4 used mismatching AV speaking style combinations (AnormVhyper, AnormVhypo, AhyperVnorm, AhypoVnorm) that were onset-matched or time-aligned, respectively. The results indicated that higher rates of mouth movement can be sufficient for the detection advantage with weak optic-acoustic associations, but, in circumstances where these associations are low, even high rates of movement have little impact on augmenting detection in noise. Furthermore, in Detection Experiment 5, in which visual stimuli consisted only of the mouth movements extracted from the three styles, there was no AV detection advantage, and it seems that this is so because extra-oral information is required, perhaps to provide a frame of reference that improves the availability of mouth movement to the perceiver. Detection Experiment 6 used a new 2I-4AFC task and the measures of false detections and response bias to identify whether visual influence in signal absent conditions is due to response bias or an illusion of hearing speech in noise (termed here the Speech in Noise, SiN, Illusion). In the event, the SiN illusion occurred for both the hyperarticulated and the normal styles – styles with reasonable amounts of movement change. For normal speech, the responses in signal-absent conditions were due only to the illusion of hearing speech in noise, whereas for hypoarticulated speech such responses were due only to response bias. For hyperarticulated speech there is evidence for the presence of both types of visual influence in signal-absent conditions. It seems to be the case that there is more doubt with regard to the presence of auditory speech for non-normal speech styles. An explanation of past and present results is offered within a new framework -the Dynamic Bimodal Accumulation Theory (DBAT). This is developed in this thesis to address the limitations of, and conflicts between, previous theoretical positions. DBAT suggests a bottom-up influence of visual speech on the processing of auditory speech; specifically, it is proposed that the rate of change of visual movements guides auditory attention rhythms ‘on-line’ at corresponding rates, which allows selected samples of the auditory stream to be given prominence. Any patterns contained within these samples then emerge from the course of auditory integration processes. By this account, there are three important elements of visual speech necessary for enhanced detection of speech in noise. First and foremost, when speech is present, visual movement information must be available (as opposed to hypoarticulated and synthetic speech) Then the rate of change, and opticacoustic relatedness also have an impact (as in Detection Experiments 3 and 4). When speech is absent, visual information has an influence; and the SiN illusion (Detection Experiment 6) can be explained as a perceptual modulation of a noise stimulus by visually-driven rhythmic attention. In sum, hyperarticulation augments the AV speech detection advantage, and, whenever speech is perceived in noisy conditions, there is either response bias to perceive speech or a SiN illusion, or both. DBAT provides a detailed description of these results, with wider-ranging explanatory power than previous theoretical accounts. Predictions are put forward for examination of the predictive power of DBAT in future studies. / Doctor of Philosophy (PhD)

This thesis is concerned with describing and experimentally investigating the nature of perceptual learning. Ecological psychology defines perceptual learning as a process of educating attention to structural properties of stimuli (i.e., invariants) that specify meaning (i.e., affordances) to the perceiver. Although such definition comprehensively describes the questions of what humans learn to perceive, it does not address the question of how learning occurs. It is proposed in this thesis that the principles of classical and operant conditioning can be used to strengthen and expand the ecological account of perceptual learning. The perceptual learning of affordances is described in terms of learning that a stimulus is associated with another stimulus (classical conditioning), and in terms of learning that interacting with a stimulus is associated with certain consequences (operant conditioning). Empirical work in this thesis investigated the effect of conditioning on pitch and speech perception. Experiments 1, 2, and 3 were designed to modify pitch perception in Shepard tones via tone-colour associative training. During training, Shepard tones were paired with coloured circles in a way that the colour of the circles could be predicted by either the F0 (pitch) or by an F0-irrelevant auditory invariant. Participants were required to identify the colour of the circles that was associated with the tones and they received corrective feedback. Hypotheses were based on the assumption that F0-relevant/F0- irrelevant conditioning would increase/decrease the accuracy of pitch perception in Shepard tones. Experiment 1 investigated the difference between F0-relevant and F0- irrelevant conditioning in a between-subjects design, and found that pitch perception in the two conditions did not differ. Experiments 2 and 3 investigated the effect of F0- relevant and F0-irrelevant conditioning (respectively) on pitch perception using a within subjects (pre-test vs. post-test) design. It was found that the accuracy of pitch perception increased after F0-relevant conditioning, and was unaffected by F0-irrelevant conditioning. The differential trends observed in Experiments 2 and 3 suggest that conditioning played some role in influencing pitch perception. However, the question whether the observed trends were due to the facilitatory effect of F0-relevant conditioning or the inhibitory effect of F0-irrelevant conditioning warrants future investigation. Experiments 4, 5, and 6 were designed to modify the perception of McGurk syllables (i.e., auditory /b/ paired with visual /g/) via consonant-pitch associative training. During training, participants were repeatedly presented with /b/, /d/, and /g/ consonants in falling, flat, and rising pitch contours, respectively. Pitch contour was paired with either the auditory signal (Experiments 4 and 5) or the visual signal (Experiment 6) of the consonant. Participants were required to identify the stop consonants and they received corrective feedback. The perception of McGurk stimuli was tested before and after training by asking participants to identify the stop consonant in each stimulus as /b/ or /d/ or /g/. It was hypothesized that conditioning would increase (1) /b/ responses more in the falling than in the flat/ rising contour conditions, (2) /d/ responses more in the flat than in the falling/ rising contour conditions, and (3) /g/ responses more in the rising than in the falling/flat contour conditions. Support for the hypotheses was obtained in Experiments 5 and 6, but only in one response category (i.e., /b/ and /g/ response categories, respectively). It is suggested that the subtlety of the observed conditioning effect could be enhanced by increasing the salience of pitch contour and by reducing the clarity of auditory/visual invariants that specify consonants. / Doctor of Philosophy (PhD)

A combination of experimental and empirical studies investigate the assumption that musical expression is communicated in marimba performance through at least two channels – sound and action. A parallel is drawn between the bodily movements and gestures occurring with expressive musical sound, and gestures produced in concurrence with speech. Experiment 1 investigated the assumption that bodily movements and gestures can enhance or diminish the perception of expression and interest in solo marimba performance when presented audio-visually compared to presentation in audio-only form. Body movement is of particular relevance here as the expressive capabilities of the marimba are relatively restricted, and the movements required to play it are visible. Twenty-four musically-trained and 24 musically-untrained observers rated auditory-only and auditory-visual presentations of 20th Century solo marimba excerpts for perceived expressiveness and interest. Performances were given by a male and a female professional musician in projected (public performance expression) and deadpan (minimised expressive features) performance manners. As hypothesised, significantly higher ratings were recorded in response to projected performances than to deadpan. The hypothesised interaction between modality and performance manner was observed. Higher expressiveness ratings were observed for projected performances, and lower ratings were observed for deadpan performances when the presentation was audio-visual compared to audio-only. Higher interest ratings were observed for projected performances when the presentation was audio-visual. Musically-trained participants recorded higher ratings than musically-untrained observers upholding the final hypothesis. The results suggest that expressive functional bodily movements and bodily gestures play an important role in marimba performer-audience communication. Findings are relevant for both performers and educators. The aim of Experiment 2 was to investigate whether the results of Experiment 1, conducted in laboratory conditions, would generalise to an ecologically valid setting – a real concert. Experiment 2 investigated audience continuous self-report engagement responses from 21 participants collected using the portable Audience Response Facility (pARF). The stimulus material was a solo marimba piece performed in a live concert. A female musician performed two musically similar sections within the piece in two different performance manners (deadpan and projected). The second order standard deviation threshold method was used to analyse signal reliability. As hypothesised, mean engagement responses were greater in the projected sample than the deadpan sample. Reliable signal was only observed in the projected sample. Differences between deadpan and projected sample mean engagement responses may be due to expressive bodily movement from the performance manner manipulation; alternatively, serial order effect, necessitated by the concert setting, may be responsible. Such experimentation in ecologically valid settings enables understanding of audience perception of live music performance as it unfolds in time. Expressive qualities of marimba players���� bodily gestures, witnessed in several projected and deadpan marimba performances in the stimulus material from Experiment 1 were analysed in Study 1. Laban Movement Analysis (LMA) observation techniques, involving embodied thinking and kinaesthetic mirroring, enabled analysis of force. Force is the third element of motion additional to temporal and spatial aspects for which technology measuring only kinematics can not account. Effort-shape analysis and notation described and recorded expressive qualities of marimba players’ bodily gestures at specific locations on the musical score. With basic training, professional percussionist performers were able to understand and apply effort-shape analysis and notation. This inspired confidence that effort-shape analysis and notation has potential as an analytical tool for performers, teachers and students. The results of Experiments 1 and 2 and Study 1 lead to the formation of a theory of bodily gestures in marimba performance. This theory accounted for functional bodily movements and bodily gestures in marimba performance based on an embodied interpretation of the musical score. Combined experimental and empirical results indicate that bodily movements and gestures can enhance perception of expressive marimba performance and therefore warrant focussed attention in pedagogy and practice. / Doctor of Philosophy (PhD)

This research focuses on the analysis of pictorial images from objects of Germanic/early Scandinavian cultures in order to discriminate elements which are only applied for decorative reasons from those which also express symbolic values. At the outset I introduced an interpretation of the terms �signs� and �symbols� in order to inform the reader to which extent these terms were applied. It appeared that techniques, such as the geographical and chronological classification, traditionally used by archaeologists and historians to analyse objects/artefacts, were not always sufficient enough to gain all information which images may offer. Sometimes it seems to be difficult to determine if certain images shown on objects from early mediaeval, central and northern European origin, were created as a space-filling decoration only or if they held additional, probably symbolic, information as well. I have investigated aspects from visual perception, as applied within the domains of psychology, visual art and design. The methods, as they are introduced in this thesis, can be used as a identification scheme, applied on objects of great diversity. I have applied them on guldgubber (little embossed gold foils), bracteates and Gotland picture-stones. Objects of great historical and geographic difference, as well as physical diversity, such as size and material were chosen purposely to create an overview of the symbolic expressions in Germanic/early Scandinavian artefacts and to test the extent of the identification method derived from the domain of visual perception. A detailed analysis of sixty four guldgubber, found in Lundeborg, near Gudme, on the island of Fyn (Denmark), is placed in an appendix. An analysis of these objects appeared to be particularly interesting because it is not known what the purpose of guldgubber were to the present day.

"July 2002" / Includes bibliographical references (leaves 324-342) / xiii, 342 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, 2002

In the last seven years a new computational approach has led to promising advances in the understanding of biological visual perception. The foundations of the approach are largely due to the work of a single man, David Marr at M.I.T. Now, after his death in Boston on November 17th 1980, research in vision will not be the same for the growing number of those who are following his lead.

Texture boundary detection (or segmentation) is an important capability of the human visual system. Usually, texture segmentation is viewed as a 2D problem, as the definition of the problem itself assumes a 2D substrate. However, an interesting hypothesis emerges when we ask a question regarding the nature of textures: What are textures, and why did the ability to discriminate texture evolve or develop? A possible answer to this question is that textures naturally define physically distinct surfaces or objects, thus, we can hypothesize that 2D texture segmentation may be an outgrowth of the ability to discriminate surfaces in 3D. In this thesis, I investigated the relative difficulty of learning to segment textures in 2D vs. 3D configurations. It turns out that learning is faster and more accurate in 3D, very much in line with what was expected. Furthermore, I have shown that the learned ability to segment texture in 3D transfers well into 2D texture segmentation, but not the other way around, bolstering the initial hypothesis, and providing an alternative approach to the texture segmentation problem.

No description available.

The purpose of this research was to develop and administer a series of treatments that resulted in evidence of Visual Problem Solving ability changes and increased levels of visual differentiation in children. Piaget has posited the possibility of a lag in the exhibition of new percepts in observable form due to psychomotor limitations. Gibson and Gagne have described various components of visual perceptual growth that emphasize first hand experiences in the environment and a problem solving orientation as possible perceptual affectors. A series of Visual Problem Solving tasks were constructed that employed the medium of photography and encouraged children to closely attend to stimuli in the visual array.The sample utilized in this investigation was comprised of 75 students equally divided between three intact second and third grade level combined classroom groups at the Burris Laboratory School, Muncie, Indiana. The three groups were assigned to experimental or control group status by use of a table of random numbers. One group received Visual Problem Solving training that stressed Perceptual Principles; a second group received Visual Problem Solving training that emphasized the traditionally taught Visual Elements of Design; and a third group served as a control which received no specific training or treatments. The subjects in all three groups were pre- and post-tested using the Children's Embedded Figures Test (CEFT) and the Motor-Free Visual Perception Test (MVPT) as measures of visual perceptual functioning. In addition to these standardized instruments, a rating scale was developed expressly for this study. The Dunn Photographic Rating Scale (DPRS) was employed for measurement of possible visual information handling differences between Groups 1 and 2 with regard to photographic activities.The data collected during this research was subjected to multivariate analysis of variance and covariance. Correlation coefficients were computed to evaluate possible relationships between the measures and to obtain estimates of instrument reliability. An alpha level of .05 was employed to test the null hypotheses. Review of the data led to the following conclusions:Subjects receiving treatments that emphasized Visual Problem Solving in conjunction with Perceptual Principles achieved significantly higher results on the Children's Embedded Figures Test than subjects in the other two groups.Analysis of data obtained from subject performance on the Motor-Free Visual Perception Test was inconclusive.Photographic performance as measured by the Dunn Photographic Rating Scale uncovered significant differences between the Perceptual Principles Group and the Elements of Design Group. The Perceptual Principles Group achieved significantly higher levels throughout the five treatments.The most important general finding in this investigation concerned the facilitating effect between Visual Problem Solving methodologies and photographic activity by children. Increases in visual perceptual performance by Perceptual Principles Group 1 provided strong support for instructional strategies that seek to guide children in the formation of higher order visual rules, and contiguity in the application of these guidelines. The evidence tentatively suggested that the photographic medium may have provided a form of visual perceptual activity that increased the mobility of the perceiver, thereby increasing the perceiver's first hand experiences with the environment and ability to isolate visual data. In addition, the lack of emphasis on psychomotor development engendered by the photographic medium was considered to be of value in eliciting new percepts in visual form.