People Interpret Robotic Non-linguistic Utterances Categorically

We present results of an experiment probing whether adults exhibit categorical perception when affectively rating robot-like sounds (Non-linguistic Utterances). The experimental design followed the traditional methodology from the psychology domain for measuring categorical perception: stimulus continua for robot sounds were presented to subjects, who were asked to complete a discrimination and an identification task. In the former subjects were asked to rate whether stimulus pairs were affectively different, while in the latter they were asked to rate single stimuli affectively. The experiment confirms that Non-linguistic Utterances can convey affect and that they are drawn towards prototypical emotions, confirming that people show categorical perception at a level of inferred affective meaning when hearing robot-like sounds. We speculate on how these insights can be used to automatically design and generate affect-laden robot-like utterances

Face familiarity, distinctiveness, and categorical perception

Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000), no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories. One possibility explored was that a choice of a distinctive face as an end-point in a morphed continuum can spuriously produce effects that resemble CP. Such morphed continua provided unequal psychological responses to equal physical steps though much more so in a better likeness paradigm than for forced-choice recognition. Thus, researchers doing almost the same experiments may produce very different results and come to radically different conclusions

Gender-related differences in physiologic color space: a functional transcranial Doppler (fTCD) study

Simultaneous color contrast and color constancy are memory processes associated with color vision, however, the gender-related differences of 'physiologic color space' remains unknown. Color processing was studied in 16 (8 men and 8 women) right-handed healthy subjects using functional transcranial Doppler (fTCD) technique. Mean flow velocity (MFV) was recorded in both right (RMCA) and left (LMCA) middle cerebral arteries in dark and white light conditions, and during color (blue and yellow) stimulations. The data was plotted in a 3D quadratic curve fit to derive a 'physiologic color space' showing the effects of luminance and chromatic contrasts. In men, wavelength-differencing of opponent pairs (yellow-blue) was adjudged by changes in the RMCA MFV for Yellow plotted on the Y-axis, and the RMCA MFV for Blue plotted on the X-axis. In women, frequency-differencing for opponent pairs (blue-yellow) was adjudged by changes in the LMCA MFV for Yellow plotted on the Y-axis, and the LMCA MFV for Blue plotted on the X-axis. The luminance effect on the LMCA MFV in response to white light with the highest luminous flux, was plotted on the (Z - axis), in both men and women. The 3D-color space for women was a mirror-image of that for men, and showed enhanced color constancy. The exponential function model was applied to the data in men, while the logarithmic function model was applied to the data in women. Color space determination may be useful in the study of color memory, adaptive neuroplasticity, cognitive impairment in stroke and neurodegenerative diseases

Beware your neighbours: interactions shape population dynamics in natural grassland communities

Interactions between species have long been recognised as being of major importance to patterns of diversity and abundance, yet our knowledge of how interactions operate and vary in natural plant communities remains incomplete. In such diverse system, interactions are both numerous and highly variable, and they depend on both abiotic and biotic context. This makes quantifying interaction strengths between species in natural communities a difficult and complex task, but it is also a necessary one if we are to uncover the driving forces underpinning this variation. Species interactions are an important component of grassland population dynamics, where plants compete for sunlight, space, nutrients and water. Furthermore, the short generation times of most grassland plant species makes them a useful system for examining the effects of interactions. The National Vegetation Survey databank, operated by Landcare Research, hosts time-series of grassland plant abundances from several hundred plots and collected over the span of several decades. I proposed to exploit the potential of this data set in order to examine the effects of interactions on plant population dynamics. My first hypothesis was that including species interactions in models of population dynamics would improve our ability to predict changes in plant abundance in natural grassland communities. To test this hypothesis, I compared the fits of a series of models which included interactions in increasingly complex and biologically meaningful ways. I found that including interactions improved predictions for the overwhelming majority of species. The most successful model included every pairwise interaction, which allowed us to estimate measures of interaction strengths between species. In turn, the distribution of these interaction strengths provided insights into potential community-level differences in stability. The results presented here suggest these differences were driven by elevation, which weakened interactions, and the presence of exotic species, who tended to have stronger interactions than native species. My second study investigated how interactions between species varied along multiple abiotic gradients. I estimated interaction strengths between focal species and four guilds of competitors — forbs, graminoids, woody species and non-woody others — occurring over a range of elevations and latitudes. Both gradients had varying effects on the mean interaction strengths of each competitor guild. On average, increasing elevation and latitude made interactions with forbs facilitative, whereas interactions with graminoids and woody species became less facilitative and more competitive. This variation in interaction effects might be a reflection of the different optima conditions for each group of species. Together, the work that makes up this thesis suggests that interactions between species can be regarded as an important driver of changes in plant abundance in these grassland communities. Plantplant interactions should be included in models of population dynamics in order to improve predictions of changes in abundance. Furthermore, including interactions also uncovers how variable their effects are, to both environmental conditions and identity of the interaction partner. In particular, the relationships between elevation, species functional guild and biological status affected species interactions in complex, and at times unexpected ways. This has important implications for our understanding of how plant interactions shape grassland community dynamics, and thereby how these communities might respond to biotic and abiotic threats

Mapping the mind with broken theodolites : contributions to multidimensional scaling methodology, with special application to triadic data, and the sorting and hierarchical sorting methods : a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Human Development Studies at Massey University

This thesis focuses on the psychological applications of Multidimensional Scaling (MDS) theory and methodology. The results are investigated of treating certain kinds of dissimilarity data (triadic data, to begin with) as comparisons between dissimilarities. This is a familiar idea but many of its implications are unexplored. First, when data are available from more than one subject, it becomes possible to apply models of individual variation, in non-metric form. The Weighted Euclidean (or INDSCAL) model is the one used most often in this thesis, but the more general IDIOSCAL model is used to investigate individual differences in the case of colour vision. The data sets need not be complete. This is important when the size of the stimulus set means that there are too many comparisons for a single subject to respond to them all. Second, Maximum Likelihood Estimation (MLE) becomes a straightforward generalisation of the standard hill-descent algorithm for minimising Stress. Third, data collected with the sorting and hierarchical sorting methods can also be regarded as dissimilarity comparisons. The convenience of the sorting method and the lesser demands it makes on subjects when the number of stimuli is large have led to its widespread use, but the best way of analysing such data is uncertain. A 'reconstructed dyad' analysis is described and shown to be better than the usual co-occurence approach in a number of examples in which evidence about the true perceptual or conceptual space is available independently. Finally, when the data are interpreted as dissimilarity comparisons, an interactive method of scaling large stimulus sets becomes possible, in which one selectively acquires incomplete data, concentrating on comparisons which are expected to contain most information about the configuration. This approach has been applied twice, with the stimuli being simple synthesised sounds in one example, and complex natural sounds (canine heartbeats) in the second, working well in both cases. The potential applications for training people to recognise sounds are briefly considered. Some possibilities for future research arising from this work are described

Considering the Prevalence of the "Stimulus Error" in Color Naming Research

In "Does the Basic Color Terms discussion suer om the Stimulus Error?" Rolf Kuehni describes a research stumbling block known as the "stimulus error, " and hints at the diculties it causes for mainstream color naming research (Kuehni, is Issue). Among the issues intrinsic to Kuehni's "stimulus error" description is the important question of what can generally be inferred from color naming behaviors based on bounded samples of empirical stimuli. Here we examine some specics of the color naming research issues that Kuehni raises. While we share Kuehni's view regarding potential problems caused by the "stimulus error" and his concern regarding its prevalence, Kueh-ni's commentary seems primarily aimed at stimulating a general discussion of color naming research implications, because the articles he critiques do not actually commit the "stimulus error" in any serious sense. Based on Kuehni's comments, we further examine some of the relevant empirical and theoretical implications for cross-cultural color naming research