bluuebunny/crossref_metadata_2025 huggingface dataset:
Extremely low voltage and high bright p-i-n fluorescent white organic light-emitting diodes
Authors: Duan Y. , Mazzeo M. , Maiorano V. , Mariano F. , Qin D. , Cingolani R. , Gigli G.
Published: March 2008

Extremely low voltage white organic light-emitting devices (WOLEDs) with fluorescent emitters are realized exploiting p-i-n structure. White light is obtained by two complementary colors system, in which the yellow and the blue emitting components are based on 5,6,11, 12-tetraphenylnaphthacene (rubrene) and 4,4-bis-2, 2-diphenylvinyl-1, 1-spirobiphenyl (Spiro-DPVBi), respectively. The effects on the device performances of various electron blocking layers and hosts for rubrene are discussed. The best device shows a luminance of 1000cd∕m2 at bias of as low as 2.9V, and 10000cd∕m2 at 4.7V with a maximum power efficiency of 8.7lm∕W. The Commission Internationale de 1’Eclairage chromaticity coordinates change from (0.36, 0.45) at 1000cd∕m2 to (0.33, 0.42) at 10000cd∕m2 showing high color stability.
Dielectric passivation effects on ZnO light emitting diodes
Authors: Wang Yu-Lin , Kim H. S. , Norton D. P. , Pearton S. J. , Ren F.
Published: March 2008

Plasma-enhanced chemical vapor-deposited SiO2 and SiNx were used to passivate ZnO heterojunction light emitting diodes (LEDs). Postdielectric deposition annealing was critical in obtaining good LED electrical and optical characteristics. No diode characteristics or light emission was observed unless the structures were annealed at 350°C after fabrication. Annealed diodes showed a band-edge electroluminescence (EL) (385nm) and a broad defect band with a peak at 930nm at room temperature. The SiO2 and SiNx had very different passivation effects in terms of the electrical and EL characteristics of the LEDs. After annealing, the SiO2 passivated ZnO LEDs showed diode I-V characteristics and emitted light. However, the annealed SiNx-passivated ZnO LEDs showed leaky diode characteristics and no light emission. We attribute these differences to the role of hydrogen on the LEDs.
Decomposition rate of cereal straw as affected by soil placement
Authors: Curtin D. , Francis G. S. , McCallum F. M.
Published: March 2008

Decomposition rates for crop residues have generally been estimated based on data obtained using buried litter bags. Because of limited soil–residue contact, the litter bag technique may not adequately simulate decomposition when residues are mixed through the soil. In field microplots, decomposition of wheat (Triticum aestivum) and barley (Hordeum vulgare) straw (autumn-incorporated at a rate of 7 t/ha) mixed through the 0–0.20 m soil layer was compared with straw decomposition in fibreglass bags (4-mm mesh) buried at a depth of 0.20 m. A surface-placed straw treatment and a no-straw control were included for comparison. Emissions of CO2 were monitored from the incorporated straw treatments and undecomposed straw was recovered after 158 days (mean soil temperature during the trial period was 8°C at 0.10 m). Emissions of CO2 from the soil‐mixed straw treatment were generally greater than from the buried bag treatment in the 2 months following incorporation. Output of CO2-C over the first 73 days averaged 83 g/m2 for the soil-mixed straw treatment compared with 61 g/m2 for the litter bag treatment and 34 g/m2 for the no-straw control. Over the entire trial, CO2-C attributable to straw (CO2-C output from straw-treated plots minus CO2-C emitted from the control) was 66% greater for soil‐mixed straw than for litter bag straw, indicating that within soil placement can have a strong and persistent effect on straw decomposition. Straw type had a small but significant (P < 0.05) effect on CO2 output (barley > wheat). Straw mass loss during the trial averaged 66% for soil-mixed straw, 32% for litter bag straw, and 13% for straw placed on the soil surface. The low recovery of soil‐mixed straw is partly due to difficulty of extracting small (<2 mm) residue fragments from the soil; however, such fragments could legitimately be considered part of the soil organic matter. The results confirm that straw that is well distributed through the soil may decompose more rapidly than would be anticipated from litter bag measurements.
Desalinisation by zone leaching: laboratory investigations in a model sand-tank
Authors: Mirjat M. S. , Rose D. A. , Adey M. A.
Published: March 2008

We report a laboratory study in a model sand-tank to investigate improvements using partial ponding over the common method of leaching salts from soils by flooding the entire area above equally spaced subsurface drains. The physical basis of the theory developed by E. G. Youngs and P. B. Leeds-Harrison was demonstrated in the model. We traced the streamline patterns for complete ponding and 3 situations of partial ponding of the soil surface to demonstrate the flow paths. We also leached saline water, initially uniformly distributed in the sand, with sweet water and recorded the breakthrough curves of the leaching water for the same situations of complete and partial ponding. The results demonstrate that partial ponding is more effective than complete ponding in that it requires less time to carry solute towards the drain and saves water of good quality needed to leach salts through drains. They also confirm the theoretical findings that more uniform leaching with less water can be achieved by constraining the infiltrating area with bunds, initially flooding only the region midway between the drains and then progressively increasing the flooded area until the entire surface above the drains is ponded.
An experimental approach to understanding the use of mistletoe as a nest substrate for birds: nest predation
Authors: Cooney Stuart J. N. , Watson David M.
Published: March 2008

Recent research has documented an unprecedented diversity of birds using mistletoes as nest-sites, and a strong preference for nesting in mistletoes has recently been demonstrated for some species. The consequences and underlying reasons for this behaviour have not been evaluated, and it is unclear whether nests in mistletoes confer advantages compared with other available substrates. Nest predation is often cited as the most important factor regulating many bird populations and is thought to influence all aspects of nest-site selection. To evaluate whether nest predation may play a role in the widespread use of mistletoe as a nest-site, we conducted an artificial nest predation experiment in a eucalypt woodland in southern New South Wales, Australia. Artificial nests were modelled on noisy friarbird (Philemon corniculatus: Meliphagidae) nests, baited with a single quail egg and checked after four days. We used logistic regression to model the rate of depredation between plant substrates, and demonstrate that, in this experiment, mistletoe nests experienced a lower proportion of predation than eucalypt nests (51.5% versus 63.8% respectively). This finding suggests that predation may influence the widespread use of mistletoe as a nest-site in a range of habitats and regions. In addition to clarifying priorities for further work on mistletoe nesting, this finding has implications for studies of nest-site selection generally, with researchers encouraged to supplement between-substrate comparisons with direct measurements of within-substrate variation.
Indexing small mammalian carnivores in the southern Kalahari, South Africa
Authors: Blaum Niels , Engeman Richard M. , Wasiolka Bernd , Rossmanith Eva
Published: March 2008

Monitoring animal populations in changing environments is crucial to wildlife conservation and management, but restrictions in resources are a recurring problem for wildlife managers and researchers throughout Africa. Land-use-induced shrub encroachment in Kalahari savannah rangelands has led to fragmentation of the landscape. Mammalian carnivores are particularly vulnerable to local extinction in fragmented landscapes, but their low numbers and their often nocturnal and secretive habits make them difficult to monitor. In this study, we tested the applicability of a passive tracking method and compared two measurement methods and index calculations for monitoring small carnivores across a grazing gradient in the southern Kalahari. During the four years of monitoring in a five-year period, we used the knowledge of indigenous Khoisan Bushmen for the identification of carnivore tracks on 640 sand transects (5 m × 250 m). Our results showed that this simple and inexpensive observation method enabled detailed monitoring of 10 small carnivore species across the grazing gradient. A binary index calculated an index based on presence/absence of a species’ tracks on each transect, whereas the track intrusion index used the number of track intrusions to each transect for each species in its calculations. For less common species, the two indices were similar in trend and magnitude, because the number of intrusions to each transect was typically 1 or 0. Usually, the two indices showed relatively strong correlations. However, species with patchy distributions of higher numbers presented difficulties for the binary index to monitor trends, but not for the track intrusion index.
Movement patterns of southern bell frogs (Litoria raniformis) in response to flooding
Authors: Wassens Skye , Watts Robyn J. , Jansen Amy , Roshier David
Published: March 2008

Within the semiarid regions of New South Wales, Australia, the endangered southern bell frog (Litoria raniformis) occupies a landscape that is characterised by unpredictable rainfall and periodic flooding. Limited knowledge of the movement and habitat-occupancy patterns of this species in response to flood events has hampered conservation efforts. We used radio-tracking to assess changes in movement patterns and habitat occupancy of L. raniformis (n = 40) over three different periods (November, January and April/May) that coincided with the flooding, full capacity and subsequent drying of waterbodies within an irrigation landscape. We assessed (1) the use of permanent and ephemeral habitats in response to flooding and drying and (2) distances moved, turning angles and dispersion of frogs during wetland flooding, full capacity and drying. Individuals remained in permanent waterbodies in November but had abandoned these areas in favour of flooded ephemeral waterbodies by January. As the ephemeral waterbodies dried, radio-tracked individuals moved back into permanent waterbodies. The movement patterns of radio-tracked individuals were significantly different in the three radio-tracking periods, but did not differ significantly between sexes. Individuals moved significantly greater distances over 24 h, in straighter lines and movements were more dispersed while they occupied ephemeral waterbodies during January than when they occupied permanent waterbodies during November and April/May. Local weather conditions did not influence movement patterns when all three tracking periods were modelled together using a single linear stepwise regression. The dynamic distribution of habitat patches over space and time, combined with changing patterns of resource utilisation and movement of L. raniformis, highlights the importance of incorporating both permanent and ephemeral habitat patches into conservation plans. Reductions in flood frequency and extent of ephemeral wetlands due to modified flooding regimes have the capacity to limit dispersal of this species, even when permanent waterbodies remain unchanged.
Australian tadpoles do not avoid chemical cues from invasive cane toads (Bufo marinus)
Authors: Hagman Mattias , Shine Richard
Published: March 2008

If invasive species are phylogenetically distinct from native taxa, divergence in intraspecific communication systems may allow control via methods that invoke behavioural responses by the invasives but not by local species. Previous work has exploited sexual signals in this respect (e.g. species-specific mate-attraction pheromones) but there is equal potential to exploit non-sexual signals, such as chemically mediated behavioural responses of anuran larvae. Cane toads (Bufo marinus), originally from Central and South America, are creating major ecological problems during their invasion through Australia. In an earlier study, we showed that cane toad tadpoles are strongly repulsed by chemical cues from crushed conspecifics, suggesting that these animals possess significant chemical communication systems. To be useful in control of toads, such a response would need to be restricted to cane toads rather than all anurans. In laboratory trials, we detected only minor behavioural responses of six native Australian anuran species to chemical cues from cane toads. Native tadpoles (both hylids and myobatrachids) either ignored the stimulus, or tended to approach it rather than to avoid it. These results are encouraging for the potential use of toad-specific chemicals to manipulate the behaviour of tadpoles in the field, with few collateral effects on native Australian anurans.
VIEWPOINT. An hypothesis to explain the linkage between kakapo (Strigops habroptilus) breeding and the mast fruiting of their food trees
Authors: Fidler Andrew E. , Lawrence Stephen B. , McNatty Kenneth P.
Published: March 2008

An important goal in the intensive conservation management of New Zealand’s critically endangered nocturnal parrot, kakapo (Strigops habroptilus), is to increase the frequency of breeding attempts. Kakapo breeding does not occur annually but rather correlates with 3–5-year cycles in ‘mast’ seeding/fruiting of kakapo food plants, most notably podocarps such as rimu (Dacrydium cupressinum). Here we advance a hypothetical mechanism for the linking of kakapo breeding with such ‘mast’ seeding/fruiting. The essence of the hypothesis is that exposure to low levels of dietary phytochemicals may, in combination with hepatic gene ‘memory’, sensitise egg yolk protein genes, expressed in female kakapo livers, to oestrogens derived from developing ovarian follicles. Only in those years when the egg yolk protein genes have been sufficiently ‘pre-sensitised’ by dietary chemicals do kakapo ovarian follicles develop to ovulation and egg-laying occurs. While speculative, this hypothesis is both physiologically and evolutionarily plausible and suggests both future research directions and relatively simple interventions that may afford conservation workers some influence over kakapo breeding frequency.
The dominance of English in the international scientific periodical literature and the future of language use in science
Authors: Hamel Rainer Enrique
Published: March 2008

Throughout the 20th century, international communication has shifted from a plural use of several languages to a clear pre-eminence of English, especially in the field of science. This paper focuses on international periodical publications where more than 75 percent of the articles in the social sciences and humanities and well over 90 percent in the natural sciences are written in English. The shift towards English implies that an increasing number of scientists whose mother tongue is not English have already moved to English for publication. Consequently, other international languages, namely French, German, Russian, Spanish and Japanese lose their attraction as languages of science. Many observers conclude that it has become inevitable to publish in English, even in English only. The central question is whether the actual hegemony of English will create a total monopoly, at least at an international level, or if changing global conditions and language policies may allow alternative solutions. The paper analyses how the conclusions of an inevitable monopoly of English are constructed, and what possible disadvantages such a process might entail. Finally, some perspectives of a new plurilingual approach in scientific production and communication are sketched.
The roots of linguistic organization in a new language
Authors: Aronoff Mark , Meir Irit , Padden Carol A. , Sandler Wendy
Published: March 2008

It is possible for a language to emerge with no direct linguistic history or outside linguistic influence. Al-Sayyid Bedouin Sign Language (ABSL) arose about 70 years ago in a small, insular community with a high incidence of profound prelingual neurosensory deafness. In ABSL, we have been able to identify the beginnings of phonology, morphology, syntax, and prosody. The linguistic elements we find in ABSL are not exclusively holistic, nor are they all compositional, but a combination of both. We do not, however, find in ABSL certain features that have been posited as essential even for a proto-language. ABSL has a highly regular syntax as well as word-internal compounding, also highly regular but quite distinct from syntax in its patterns. ABSL, however, has no discernable word-internal structure of the kind observed in more mature sign languages: no spatially organized morphology and no evident duality of phonological ­patterning.
Diversity and citizenship in the curriculum
Authors: Starkey Hugh
Published: March 2008

This article comments on keynote speeches given by Keith Ajegbo and Audrey Osler. The programme of study for citizenship derived from the Crick report and did not emphasise race equality and national unity for security. Osler argues that the Ajegbo review addressed teaching of ethnic,
religious and cultural diversity but did not confront the inadequacies of British democracy or reassert social justice, a sense of shared humanity and a commitment to human rights. Proposing, let alone imposing, a definition of Britishness is futile, but it is possible to promote cosmopolitan
patriotism supported by explicit principles, concepts and values.
Citizenship education and the Ajegbo report: re-imagining a cosmopolitan nation
Authors: Osler Audrey
Published: March 2008

Following the 2005 London bombings, there is widespread public debate about diversity, integration, and multiculturalism in Britain, including the role of education in promoting national identity and citizenship. In response to official concerns about terrorism, a review panel was invited
to consider how ethnic, religious and cultural diversity might be addressed in the school curriculum for England, specifically through the teaching of modern British social and cultural history and citizenship. The resultant Ajegbo report proposes a new strand on 'identity and diversity: living
together in the UK', be added to the citizenship education framework. While the report gives impetus to teaching about diversity, it does not strengthen the curriculum framework proposed in the Crick report. It fails to adopt a critical perspective on race or multiculturalism or adequately
engage with young people's lived experiences of citizenship within a globalised world. I analyse how the review panel conceptualises identity, democracy and diversity. I then consider its assumptions about racism, human rights, and citizenship education, concluding with reflections on how
citizenship education might be developed in the task of re-imagining the nation and meeting the needs of emergent cosmopolitan citizens.
Citizenship learning and political participation: the case of Latin American-Canadians
Authors: Ginieniewicz Jorge
Published: March 2008

This article explores the informal learning processes and the changes in the values of a group of 200 Latin American immigrants to Canada. Results show that the majority of the respondents underwent at least one political or civic learning process, like increasing tolerance or environmental
responsibility. The findings also suggest a number of tensions between the set of values brought from the home countries and those incorporated in the home country. The author argues that these tensions led some interviewees through a process of transformative learning.
A Comparison of the Influence of Handle Load and of Unfavourable Atmospheric Conditions on a Tracking Task
Authors: Carpenter A.
Published: March 2008

An experiment was made to determine the extent to which the performance of a tracking task was adversely influenced by simulated tropical environmental conditions, by comparing this effect with that of loading the control handle with weights. The pursuitmeter used was similar to that used by Mackworth (1948) when he showed that the accuracy of performance was reduced under tropical conditions. The score of error was the total angular separation between the target and follower pointers expressed in arbitrary units. It was found that as the room temperature was raised from approximately 80° to 90° on the Effective Temperature scale, this score increased in the ratio 1–13, an increase which was also obtained by increasing the load on the control handle from 8 to 30 lb. There were also indications that the effect of room temperature was greater with higher handle loads. The effect on performance was not correlated with rectal temperature or with the amount of weight lost.
The Threshold for Sudden Changes in the Velocity of a Seen Object
Authors: Hick W. E.
Published: March 2008

The difference threshold for the velocity of a seen object was measured by the method of constant stimuli, using two categories. An approximate correspondence with Weber's law was found, the divergence from it appearing, in general, as an increase of the threshold at both ends of the range of initial velocities. The Mean Threshold (0·5 probability of perception, corrected for guessing) was, in favourable conditions, about 12 per cent, of the initial velocity. Whether the stimulus was an increase or a decrease of velocity made no marked difference. With two moving objects, which converged, crossed, and then diverged, both suffering the same change of velocity, the threshold was higher.

Velocity changes as low as 2 · 5 per cent, elicited a significant proportion of correct responses. Some theoretical points in connection with this are discussed. Responses to blank stimuli showed a strong tendency to guess “slower,” which tendency differed significantly in degree between most of the experimental conditions. Tests with reduced exposure times showed that exposures could be as short as 0 · 5 second (the velocity change occurring in the middle of the exposure) without appreciable detriment.
Stimulus Intensity and Attention in Relation to Learning Theory
Authors: Berlyne D. E.
Published: March 2008

Three experiments are described which test the hypothesis that the more intense of two stimuli will, ceteris paribus, be more likely to receive attention. It is assumed that an objective behavioural manifestation of attention to a given stimulus is a preference for responding to it rather than to another which is present at the same time.

In all three experiments, successions of pairs of visual stimuli interspersed with single stimuli were presented to the subject, and he was instructed to respond to either (by pressing its corresponding morsekey), but not both, in the case of the pairs. The first two experiments reveal significant tendencies to respond to the larger and the brighter stimulus respectively. In the third experiment, there was a tendency, but a statistically insignificant one, to respond to a constant rather than to a flickering stimulus.

It is shown that the attraction of attention by a more intense stimulus follows from Hull's system with the addition of his new variable, “stimulus-intensity dynamism (V),” and it is suggested that it may thus be possible to add attention to the phenomena that can be integrated with an objective behaviour theory.
Figural After-Effects in Stroboscopic Motion
Authors: Weiskrantz L.
Published: March 2008

The present investigation is designed to determine whether figural after-effects of the type reported by Köhler and Wallach occur in stroboscopic motion following prolonged visual fixation of a stationary pattern. The lengths of the paths of two simultaneously presented spots in stroboscopic motion were adjusted so that they appeared equal to each of the 21 subjects. Each subject then fixated a satiation pattern for two minutes, after which he reported whether the paths, unchanged by the experimenter, were equal or not, and in which direction he observed a distortion, if any. The satiation pattern was so designed that a prediction of a distortion in one direction could be made in the subject's first judgment, while a slight change in the arrangement would yield a prediction of a distortion in just the opposite direction in the second judgment. The results are taken to support the finding Köhler and Wallach that the contours of a test pattern recede from the contours of the satiation pattern, even when the test pattern is a stroboscopic one.
The Multiple Criterion Technique of Subjective Appraisal
Authors: Hopkinson R. G.
Published: March 2008

A technique is described by which, the quantitative connection between physical aspects of a stimulus situation and subjective aspects of the perceptual response may be conveniently and reliably determined. The subject is given control of one of the significant physical variables such, for instance, as brightness, and is asked to set this variable to correspond In turn with a limited number of defined criteria relating to a subjective variable such as glare-discomfort It is found that each criterion acts as a check upon judgments made in terms of the others, so that the scatter of the control settings Is less than when a single criterion is used The functional relationship between the physical and the subjective variable can be estimated, and provided care Is taken in the design of the experiment and In the selection of observers, consistent results are obtained.

This technique has been applied during the past ten years to a wide range of visual problems which Include those of the visibility of radar echoes, the visibility of street-lighting from the air, discomfort-glare and ease of reading. It Is thought that It might find wide application not only in applied Psychological work but in the investigation of problems of theoretical import.
The Influence of Interpolated Recall upon Recognition
Authors: Belbin Eunice
Published: March 2008

An experiment was designed to show how immediate recall may affect recognition. A number of subjects were shown a picture. Some were asked to recall it and were then given a recognition test. Others were given only the recognition test after the same interval. Only 4 of the 16 subjects who had recalled it identified it; whereas 14 of the 16 others did so. A second experiment gave similar results.

Recall was constructed round dominant items of the picture. This distribution of emphasis together with the acceptance of an invented detail as genuine were the common causes of errors in subsequent recognition. Both the dominant and invented items in recall were those which became most obviously merged into an organization of related experiences and in consequence those which militated against subsequent recognition.

The recognition test was applied in two further groups of 16 subjects with a change in one of the dominant details (i.e. the wording). The number of subjects who now correctly identified the remainder of the material was 9 when there was no intermediate recall, and nil when immediate recall of the original material was interposed.
On the Tunnel Effect
Authors: Burke Luke
Published: March 2008

The experiments described in this paper consist of presenting observers with two similar objects in successive movement in the same plane but of which the end of the first and the beginning of the second are hidden by a screen (tunnel). Under proper experimental conditions the impression received is one of continuous and uniform movement by a single object passing behind the screen.

The hidden phase of this movement assumes all of the characteristics of true, visible movement for its entire extent, and any lengthening of the duration of the invisible phase gives the impression of a momentary halt behind the screen at a definite point. A modification of the position or of the relative orientation of the visible portions of the trajectory influences the apparent form of its invisible portion. This form can be made to assume the aspects of complicated curves which are sketched and described by different observers with remarkable consistency.

All these phenomena are dependent upon the objctive conditions: the speed of the objects while they are visible, the length of the tunnel, the duration of the invisible phase, the relative position of the visible portions of the trajectory; and they vary systematically with these conditions. As one or other of these conditions is varied, the impression of continuity may give way to one of a simple succession of independent movements.

It is thought that the absence of sensory qualities justifies the use of the term “amodal data” to describe the way in which the hidden movement phase makes itself known to the observer. These “amodal data” form the bridge between the modal phases and become an integral part of the total sensory experience. These properties are determined by the nature of the complex system of excitations in the same way as those of the modal phases and one can thus consider this amodal aspect of the combined experience as a truly perceptual phenomenon.
The Relation of an Environmental Variable to Performance in a Prolonged Visual Task
Authors: Fraser D. C.
Published: March 2008

In a previous paper (Fraser, 1950) on the relation between angle of display and performance in a prolonged visual task (Mackworth's Clock Test), it was suggested that the presence or absence of the experimenter might affect performance on vigilance tasks. In Mackworth's original experiments (Mackworth, 1950) the subject was in a closed cabinet by himself, and as far as possible all external noise and stimuli were excluded. In the angle of display experiment, the writer sat in the same room as the subject, out of his sight, and there was no particular attempt to exclude the ordinary external noises, etc. It seemed worth while to follow up the previous experiment with another to test the hypothesis that the presence or absence of the experimenter might influence performance in such a task. A new apparatus was devised for this purpose, which possesses some advantages over the Clock Test.
Entropy and Choice Time: The Effect of Frequency Unbalance on Choice-Response
Authors: Crossman E. R. F. W.
Published: March 2008

A human subject making a sequence of choice-responses is considered as a channel transmitting information. Earlier work suggests that the rate of transmission is limited, and so that response time is proportional to the “entropy” of the source of signals. Entropy is reduced by unbalance in the relative frequency of the possible signals according to the formula, sum (p log p). Unbalance should therefore reduce average response time This prediction is tested in a card-sorting task. The subjects sorted playing-cards into classes in various ways; times taken were proportional to calculated entropy-per-card. Departures from the expected results occurred and were found to be due to differences in perceptual difficulty of discriminations. Some incidental results are mentioned.
Visual Factors in Auditory Localization
Authors: Jackson C. V.
Published: March 2008

Previous experiments showing the importance of visual factors in auditory localization are shown to have been insufficiently quantitative.

In the first Experiment, bells were rung and lights shone on the same or different vectors, eleven subjects indicating which bell had rung. In the second Experiment, a puff of steam was seen to issue from a kettle whistle with no whistling sound, while similar whistles were sounded by compressed air on that or another vector. Twenty-one subjects cooperated.

The addition of a visual stimulus at 0° deviation increased the percentage of correct responses significantly in the second, and insignificantly in the first experiment. At 20°-30° deviation the proportion of naive responses to the visual cue was 43 per cent. in the first and 97 per cent, in the second experiment. At greater angular deviations, the proportion of naive responses fell to chance level in the first, but remained significant in the second experiment, even at 90°. The “visuo-auditory threshold” was found to be 20°-30°, but might be much larger if there were more grounds for supposing the two stimuli to be from the same source in space.
Fixations, Position Stereotypes and Their Relation to the Degree and Pattern of Stress
Authors: Knöpfelmacher F.
Published: March 2008

We have tested Maier's hypothesis that the strength of behaviour stereotypes elicited in an insoluble problem situation is a function of stress. Forty-six white rats of Wistar stock were split into two groups, which were given an insoluble problem in a water discrimination unit under two widely different degrees of punishment. Those animals who developed position stereotypes were assigned to two subgroups within each group and were given a soluble discrimination problem under conditions of 50 and 100 per cent. punishment respectively. The strength of stereotype was measured in terms of the stereotype-breaking score.

It was found that animals trained under low punishment developed the more persistent stereotypes. Animals trained under 100 per cent, punishment developed the less persistent stereotypes and the longer spans between stereotype breaking scores and the learning criterion. The behaviour of four animals in the low punishment group was closely akin to what Maier calls “abnormal fixation”; the subgroups containing them were riot unimodally distributed. Punishment differentiated response latencies which furnished evidence that the fixated animals mastered the soluble problem, in spite of not responding appropriately.
On the Figural After-Effect
Authors: George F. H.
Published: March 2008

Two experiments were carried out on the figural after-effect. The first was intended to discover whether the figural after-effect did in fact take place with statistically significant universality. The method of scoring is relevant to the question of statistical significance, but at the best the figural after-effect appears to occur in only a slightly significant manner under the first conditions used. These involved the viewing of a single circle displaced to the left of a fixation point (the inspection-figure) and so placed that if it were superimposed on the second figure—which consisted of two squares on either side of the fixation-point—the circle completely encircled the left-hand square. The second figure is called the test-figure. The fixation point of the inspection-figure was fixated for 25 seconds with one eye, and then the test-figure was substituted and viewed with the opposite eye. A decision was then given by the observer as to the relative size of the squares. Eye-dominance did not appear to be connected with these after-effect processes.

In the second experiment, however, the statistical significance of the occurrence of the after-effects was undoubted. There were two changes in experimental conditions: the instructions to the observers were changed somewhat and a second circle was introduced into the inspection-figure. No difference of any kind was found to occur in the figural after-effect when the test-figure and inspection-figure were displaced horizontally and when they were displaced vertically, and there appeared to be a precisely opposite effect to that predicted when the test-figure and the inspection-figure were actually superimposed.

The most important finding was that, whereas in the first experiment the after-effect occurred with a frequency which was barely significant statistically, it occurred on every occasion under the different conditions of the second experiment.
The after Effect of Seen Movement on a Plain Field
Authors: Grindley G. C. , Wilkinson R. T.
Published: March 2008

Twenty laboratory subjects were asked to fixate the centre of a rotating spiral disc, under conditions where all of them, on stopping the disc, obtained the well known illusion of apparent expansion outwards. In this experiment, instead of stopping the disc, a completely uniform white surface was substituted and it was found that though the borders of the surface appeared to remain still, the surface itself showed apparent expansion in nearly all cases.
Frustration and Stereotyped Behaviour in Human Subjects
Authors: Jones Leonard C. T.
Published: March 2008

The investigation was designed to show the effects upon behaviour of three different durations of frustration, and two degrees of motivation during the frustrating period. Frustration was induced in 144 subjects by setting them the task of “learning” an insoluble temporal maze; they had to record their responses by pressing on one or other of two morse-type keys. Its effect was measured in terms of: (1) The time taken to learn a soluble maze introduced, without the subjects' knowing it, by changing the system of “rewarding” responses from one based on chance to one based on the constant repetition of a pattern requiring the responses: Left—Right—Right, for its solution. (2) The tendency for the subjects to show stereotypy of behaviour by responding on the same key for a number of trials in succession without reaching a solution. (3) The pressure exerted on the response keys, which was taken to be a measure of vacillation.

Predictions that the time taken to learn the soluble task, and the stereotypy, would increase in direct relation to the duration of the frustrating period and the degree of motivation were tested.

It was found that, while there was an immediate increase in both the time taken to learn the soluble task and the stereotypy after a short period of frustration, a point was reached under conditions of prolonged frustration after which no further increase occurred and some adjustment to the situation was shown.

Some confirmation of the effect of increase in motivation in the direction predicted was obtained in all cases, but the differences were not statistically significant. The rankings of the subjects according to the time taken to learn the soluble task and the degree of stereotypy were found to be closely correlated. A definite tendency towards increased vacillation of response was seen in many of the records during the period when frustration might have been expected to have been at its peak.

These findings are discussed in relation to Maier's theory of frustration and to Selye's concept of a “general adaptation syndrome.” The latter theory is more suitable for the interpretation of the results of the present investigation.
Discrimination of Size by Sight and Tough
Authors: Kelvin R. P.
Published: March 2008

The experiment was designed to discover whether accuracy of discrimination differs when the discrimination is made in only one sense from when it is made across two senses. The evidence produced by the experiment does not warrant one to conclude that such a difference exists. The absence of such differences has been considered in relation to more general perceptual problems.
Strength Duration Curves for Electrical Stimulation of the Human Eye
Authors: Howarth C. I.
Published: March 2008

Baumgardt's surprising report of a minimum at about 30 milliseconds in the strength-duration curve for electrical stimulation of the human eye is confirmed. Arguments are presented against his explanation of the phenomenon.

An alternative hypothesis is developed: that the complex strength-duration curve is due to the interaction of on and off processes, which are separately excited by the make and break of the current: that these processes summate when separated by 30 milliseconds but are mutually inhibitory at 70 milliseconds: that these processes are the same as those known to be aroused by light. Two new experiments are designed to test this hypothesis, and the predicted result has been obtained from each.

Experiments are devised which show that the site of stimulation is the retina.

The accuracy of the method is discussed. Over the range 10 to 100 milliseconds distortion is found to be small. For shorter pulses distortion is to be expected in all cases, and it is suggested that the chronaxie is an expression merely of the condenser effect of the tissues. The use of this term should be discontinued in connection with stimulation through the skin.

Some parallels between these results and brightness comparison experiments with light are pointed out. The nature and location of the interaction is discussed.
Response-Duration of Lever Pressing in the Rat
Authors: Hurwitz H. M. B.
Published: March 2008

Two aspects of the lever-holding behaviour of rats in a Skinner-box have been analysed: firstly, the changes in the duration of the responses during the acquisition and experimental extinction phase, and, secondly, the bunching of responses during the experimental extinction phase. The response-durations on the first few acquisition trials were found to be bimodally distributed, but to become stabilized at 0.42 seconds as practice increased. During experimental extinction response-durations increased. The rate of increase depended on the conditions of secondary reward. Rats who had the source of secondary reward removed, or restricted, yielded a steeper slope than those who responded under the same conditions of secondary reward as during training.

The analysis of the extinction scores revealed that unrewarded responses were emitted in groups. Response-group latencies were shown to progress as a positive function of the number of response-groups, and the average response-duration for consecutive response-groups to increase progressively. The slope of the duration curve plotted for successive response-groups increased, and this was related to an increase in the value of the time-intercept for successive response-groups.
An Illusion of Movement Complementary to the Horizontal-Vertical Illusion
Authors: Reid R. L.
Published: March 2008

Blindfolded subjects moved a stylus held in the hand over a standard distance of 4.5 ins. in a given direction. They then attempted to move the same distance in a direction at right angles to the first. Eight combinations of movements were investigated. The results reveal an illusion such that the extent of movements to left or right across the body is underestimated, while the extent of movements towards or away from the body in the mid-line is overestimated. The illusion applies to speed as well as extent of movement. Movement up or down in a vertical plane is equivalent to movement towards or away from the body in a horizontal plane.

The interaction of this illusion with the well-known horizontal-vertical illusion of visual perception explains a failure to find any net illusory effect where lines visually displayed in different orientations were matched for length by unseen movements in similar orientations.

Whether the visual and movement illusions simply co-exist or whether they are functionally related is not yet clear.
Tactile-Kinaesthetic Perception of Straightness in Blind and Sighted Humans
Authors: Hunter Ian M. L.
Published: March 2008

A comparison is made between the tactile-kinaesthetic perception of straightness in twenty blind and twenty sighted subjects. Both types of subject are found to perceive a “plus curved” edge as straight, but this curve is significantly less for the blind than for the sighted, i.e. the blind subjects' judgments correspond more closely to the objective straight. Furthermore, the blind, both as individuals and as a group, are significantly finer in their judgments and more consistent. These results are thought to be explained in terms of the more highly developed organisation of the blind's tactile-kinaesthetic perception.
Selective Effects of an Anaesthetic Drug on Cognitive Behaviour
Authors: Steinberg Hannah
Published: March 2008

The prediction has been tested that under the influence of an anaesthetic drug, nitrous oxide, cognitive performances undergo differential impairment, the extent of which is positively correlated with the “complexity” of the task, Ten kinds of performance were investigated, ranging from speed of finger tapping to reasoning by analogy. The relative complexity of each task was determined, in accordance with conventional criteria, from its respective qualitative category or “level”—relational, associative, and motor—and within each category from qualitative analysis of the component processes involved in its execution. A simple group difference design was used, involving two groups of 50 subjects each, matched for age and sex.

Significant deterioration as a consequence of drug administration occurred in the performance of all tasks. On the whole, the more complex a task the more did it tend to be impaired. Motor performances were, however, impaired to a greater extent than had been predicted. The possible significance of these findings is discussed.
The Role of Spatial Stimuli in the Perception of Shape.: Part I
Authors: Langdon J.
Published: March 2008

Arising from earlier studies of shape constancy (Langdon, 1951; 1953) an attempt is made to examine the rôle of spatial-surround cues in shape perception, as distinct from cues provided by the object. A series of shapes is compared in total darkness, firstly with shapes stationary and secondly with shapes rotating continuously. The findings are compared with those obtained in normal illuminated surrounds. The results indicate that surround cues play an important part in perception of orientation, and hence perception of shape. An explanation is suggested involving the use of surround cues as “anchorage” or “reference” frames. This is investigated further in Part II of this paper by an attempt to modify the character of the surround cues in a controlled way.
Effects of Nitrous Oxide on Reactions to “Stress”
Authors: Russell Roger W. , Steinberg Hannah
Published: March 2008

It has been demonstrated that exposure to the stress of a situation involving conflict or frustration may interfere significantly with subsequent learning. Behaviour under stress is characterized by experiences of “anxiety” and by widespread physiological changes. Inhalation of nitrous oxide has the general effect of reducing the extent of these symptoms.

The present investigation using insoluble and soluble problems has demonstrated that both nitrous oxide and exposure to stress impair learning; but that, when subjects are exposed to stress while under the influence of the drug, the effects of the stress on subsequent learning are abolished. It is suggested that these empirical results may be accounted for either in terms of “anxiety-reduction” or in terms of transfer effects.
Fatigue during Prolonged Performance on a Simple Compensatory Tracking Task
Authors: Siddall G. J. , Anderson D. M.
Published: March 2008

Two basic activities are involved in radar operating, watchkeeping and target tracking. Deterioration of watchkeeping performance has been explained by a hypothesis which relates absence of sensory variation and failure to attend to one part of the display continuously (Broadbent, 1951). This paper describes a preliminary experiment to examine deterioration on a simple compensatory tracking task.

Twenty-one subjects were each tested for an uninterrupted period of two hours. They were required to keep a target correctly aligned by cranking a handwheel at a constant speed, and it was expected that failures to attend to the display would result in target deviations. Analysis of the results showed that both number of errors and mean duration of errors increased significantly in consecutive half-hour periods, and that there were large individual differences in performance.