Aspects of the biology of the little shag (Phalacrocorax melanoleucos brevirostris Veillot 1817) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University

Aspects of the biology of the little shag (Phalacrocorax melanoleucos brevirostris Veillot) were examined from December 1980 until April 1983 at Hamilton's and Sexton's Lagoons in lowland Manawatu. Body measurements and plumage patterns of both sexes are taken from dried specimens. Although females tend to be smaller, the differences are not significant. Plumage patterns, based on the proportion of white, are listed, and possible reasons for plumage differences between New Zealand and Australia discussed. Postures and behaviour patterns are documented, and related to ordinal and family members. The most distinctive postures and behaviour patterns relate to courtship and sexual activities. Aspects of breeding ecology are recorded, and comparisons between New Zealand and Australian populations made from records of the respective nest record schemes. Fundamental differences occur, possibly due to the unpredictable fluctuations which seem to characterise the Australian freshwater environment. Seasonal and daily time budgets are detailed at both lagoons. Rest and self-maintenance activities decrease during breeding, and tend to occur at dawn and evening. The variable relation of movement and reproductive activities is discussed in terms of season, phase of breeding, and time of day

How do changes in speed affect the perception of duration?

Six experiments investigated how changes in stimulus speed influence subjective duration. Participants saw rotating or translating shapes in three conditions: constant speed, accelerating motion, and decelerating motion. The distance moved and average speed were the same in all three conditions. In temporal judgment tasks, the constant-speed objects seemed to last longer than the decelerating objects, which in turn seemed to last longer than the accelerating stimuli. In temporal reproduction tasks, the difference between accelerating and decelerating stimuli disappeared; furthermore, watching an accelerating shape lengthened the apparent duration of the subsequent (static) display. These results (a) suggest that temporal judgment and reproduction can dissociate for moving stimuli because the stimulus influences the apparent duration of the subsequent interval, and (b) constrain theories of time perception, including those which emphasize memory storage, those which emphasize the existence of a pacemaker-accumulator timing system, and those which emphasize the division of attention between temporal and non-temporal information processing

Stimulus Repetition and the Perception of Time: The Effects of Prior Exposure on Temporal Discrimination, Judgment, and Production

It has been suggested that repeated stimuli have shorter subjective duration than novel items, perhaps because of a reduction in the neural response to repeated presentations of the same object. Five experiments investigated the effects of repetition on time perception and found further evidence that immediate repetition reduces apparent duration, consistent with the idea that subjective duration is partly based on neural coding efficiency. In addition, the experiments found (a) no effect of repetition on the precision of temporal discrimination, (b) that the effects of repetition disappeared when there was a modest lag between presentations, (c) that, across participants, the size of the repetition effect correlated with temporal discrimination, and (d) that the effects of repetition suggested by a temporal production task were the opposite of those suggested by temporal judgments. The theoretical and practical implications of these results are discussed

On the Chernoff distance for asymptotic LOCC discrimination of bipartite quantum states

Motivated by the recent discovery of a quantum Chernoff theorem for asymptotic state discrimination, we investigate the distinguishability of two bipartite mixed states under the constraint of local operations and classical communication (LOCC), in the limit of many copies. While for two pure states a result of Walgate et al. shows that LOCC is just as powerful as global measurements, data hiding states (DiVincenzo et al.) show that locality can impose severe restrictions on the distinguishability of even orthogonal states. Here we determine the optimal error probability and measurement to discriminate many copies of particular data hiding states (extremal d x d Werner states) by a linear programming approach. Surprisingly, the single-copy optimal measurement remains optimal for n copies, in the sense that the best strategy is measuring each copy separately, followed by a simple classical decision rule. We also put a lower bound on the bias with which states can be distinguished by separable operations.Comment: 11 pages; v2: Journal version; Minor errors fixed in Section I

The effect of interstimulus interval on sequential effects in absolute identification

In absolute identification experiments, the participant is asked to identify stimuli drawn from a small set of items which differ on a single physical dimension (e.g., 10 tones which vary in frequency). Responses in these tasks show a striking pattern of sequential dependencies: The current response assimilates towards the immediately preceding stimulus but contrasts with the stimuli further back in the sequence. This pattern has been variously interpreted as resulting from confusion of items in memory, shifts in response criteria, or the action of selective attention, and these interpretations have been incorporated into competing formal models of absolute identification performance. In two experiments, we demonstrate that lengthening the time between trials increases contrast to both the previous stimulus and the stimulus two trials back. This surprising pattern of results is difficult to reconcile with the idea that sequential dependencies result from memory confusion or from criterion shifts, but is consistent with an account that emphasizes selective attention. </jats:p

The effect of stimulus range on two-interval frequency discrimination

It has traditionally been thought that performance in two-interval frequency discrimination tasks decreases as the range over which the standard tone varies is increased. Recent empirical evidence and a reexamination of previous results suggest that this may not be the case. The present experiment found that performance was significantly better when the standard roved over a wide range (1500 Hz) than a narrow range (30 Hz). This pattern cannot readily be accommodated by traditional models of frequency discrimination based on memory or attention, but may be explicable in terms of neural plasticity and the formation of perceptual anchors

Psychophysics and the judgment of price: judging complex objects on a non-physical dimension elicits sequential effects like those in perceptual tasks

When participants in psychophysical experiments are asked to estimate or identify stimuli which differ on a single physical dimension, their judgments are influenced by the local experimental context — the item presented and judgment made on the previous trial. It has been suggested that similar sequential effects occur in more naturalistic, real-world judgments. In three experiments we asked participants to judge the prices of a sequence of items. In Experiment 1, judgments were biased towards the previous response (assimilation) but away from the true value of the previous item (contrast), a pattern which matches that found in psychophysical research. In Experiments 2A and 2B, we manipulated the provision of feedback and the expertise of the participants, and found that feedback reduced the effect of the previous judgment and shifted the effect of the previous item’s true price from contrast to assimilation. Finally, in all three experiments we found that judgments were biased towards the centre of the range, a phenomenon known as the “regression effect” in psychophysics. These results suggest that the most recently-presented item is a point of reference for the current judgment. The findings inform our understanding of the judgment process, constrain the explanations for local context effects put forward by psychophysicists, and carry practical importance for real-world situations in which contextual bias may degrade the accuracy of judgments

Preimpoundment Ichthyofaunal Survey of the Piney Creek Watershed, Izard County, Arkansas

Piney Creek is a clear medium-size tributary of White River in a region of the Ozarks that is undergoing rapid environmental change. Piney Creek is characterized by a very diverse ichthyofauna, although increased sedimentation due to poor agricultural practices and gravel mining threatens to destroy much natural habitat and eventually may cause extirpation of some species. The wide diversity of 44 species is related to variety of habitat and the proximity of a large reservoir, and not to differences in the physicochemical environments. Fish density ranged from 15,100 to 21 fish/ha, greatest concentrations being in headwater pools. For the three most numerous cyprinids, mean weight per individual was greater in pools than in riffles. Okkelbergia aepyptera was collected for the second time in Arkansas (Harp and Matthews, in press), and a range extension for Notropis sabinae is reported