Some comments on visual perception and the use of video playback in animal behavior studies

Video playback experiments are potentially powerful tools in behavioral research. A video screen mimics natural color, brightness, texture, and motion to humans (for which it was designed) because monitors stimulate human photoreceptors in approximately the same relative proportions as the stimuli that they mimic. Because most animals have vision that is very different from that of humans their cones may be stimulated very differently from ours, and an image that looks excellent to us may be unrecognizable to them, and vice versa. In this article we summarize how the simulation of a monitor works and the ways it can go wrong, using a bird and a fish model retina as examples. Finally we make some recommendations for minimizing some of these problems. Received: 10 November 1999 / Received in revised form: 22 February 2000 / Accepted: 2 March 2000     

Considerations in video playback design: using optic flow analysis to examine motion characteristics of live and computer-generated animation sequences

The increasing use of the video playback technique in behavioural ecology reveals a growing need to ensure better control of the visual stimuli that focal animals experience. Technological advances now allow researchers to develop computer-generated animations instead of using video sequences of live-acting demonstrators. However, care must be taken to match the motion characteristics (speed and velocity) of the animation to the original video source. Here, we presented a tool based on the use of an optic flow analysis program to measure the resemblance of motion characteristics of computer-generated animations compared to videos of live-acting animals. We examined three distinct displays (tail-flick (TF), push-up body rock (PUBR), and slow arm wave (SAW)) exhibited by animations of Jacky dragons (Amphibolurus muricatus) that were compared to the original video sequences of live lizards. We found no significant differences between the motion characteristics of videos and animations across all three displays. Our results showed that our animations are similar the speed and velocity features of each display. Researchers need to ensure that similar motion characteristics in animation and video stimuli are represented, and this feature is a critical component in the future success of the video playback technique.     

Avian colour vision and avian video playback experiments

Video playback potentially allows the presentation, manipulation, and replication of realistic moving visual stimuli, in a way that is impossible with real animals or static dummies, and difficult even with mechanical models. However, there are special problems attached to the use of this technology; this article concentrates on the problem of accurate colour rendition. Video and television simulate the colour of objects rather than reproduce the spectrum of light that they naturally emit, transmit, or reflect. This simulation is achieved by using relatively narrow waveband light to stimulate the cone cells in the retina in a similar pattern to that produced by the natural object. However, species differ in the spectral tuning of their photoreceptors, so a faithful colour rendition for a human is unlikely to be achieved for another species. This problem is discussed with special reference to birds, a taxon renown for its colourfulness and frequent use in behavioural experiments but which has a very different colour vision from that of humans. We stress that the major pitfalls that can arise when using video playback with avian subjects can also occur in ’normal’ behavioural experiments. However, the problems of faithful colour rendition are particularly severe with video, and the major benefits that the technology brings will only be realised under a limited range of circumstances, with careful validation experiments. Received: 24 January 2000 / Received in revised form: 28 March 2000 / Accepted: 1 April 2000     

Are there lessons from negative results in studies using video playback?

The use of video playback is a growing practice in animal behaviour. Studies that lead to unpredicted negative results are often considered failures and remain unpublished. In this article I review some of the published and unpublished studies that have led to negative results. Analysis of these studies suggests that no particular problem is responsible for more than a small number of negative results. I suggest further investigation of the potential causes of these negative results to assess their importance to the outcome of video playback experiments. Received: 31 January 2000 / Received in revised form: 27 March 2000 / Accepted: 28 March 2000     

Playback experiments: design and analysis

The scientific value of the outcome of an experiment is closely related to its design and analysis. This article deals with the design issues of pseudoreplication (whether the experimental design has the statistical features needed to answer the question as posed) and execution errors (problems arising from how the experiment was conducted). Three issues of analysis are also dealt with: the number and type of response measures to record; how measures should, and should not, be combined into a single response measure; and how to interpret an apparent lack of response. Interactive playback is considered separately because it raises its own specific design and analysis issues. Although the examples generally refer to video playback, these issues are common to all experiments in behaviour. Received: 23 September 1999 / Received in revised form: 24 February 2000 / Accepted: 25 February 2000     

Considerations on the use of video playbacks as visual stimuli: the Lisbon workshop consensus

This paper is the consensus of a workshop that critically evaluated the utility and problems of video playbacks as stimuli in studies of visual behavior. We suggest that video playback is probably suitable for studying motion, shape, texture, size, and brightness. Studying color is problematic because video systems are specifically designed for humans. Any difference in color perception must lead to a different color sensation in most animals. Another potentially problematic limitation of video images is that they lack depth cues derived from stereopsis, accommodation, and motion parallax. Nonetheless, when used appropriately, video playback allows an unprecedented range of questions in visual communication to be addressed. It is important to note that most of the potential limitations of video playback are not unique to this technique but are relevant to all studies of visual signaling in animals. Received: 20 October 1999 / Accepted: 5 November 1999     

Apparent decoupling of prey recognition ability with prey availability in an insular snake population

Numerous studies on the feeding behavior of snakes have reported the consistency of tongue-flick responses with their natural diets. For representatives of widely distributed, dietary generalist species from particular localities, we can expect that their tongue-flick responses to potential prey unavailable in their original habitats have been reduced whereas those to prey common in the habitats have been enhanced. To test this hypothesis, intraspecific variation in tongue-flick responses to prey chemicals was examined using ingestively naive snakes (Elaphe quadrivirgata) from dietarily different populations: populations from the main Japanese island, where the snakes' diet predominantly consists of sympatric frogs, and from Mikura-jima Island, where no frogs occur and the snakes thus chiefly prey on lizards. We presented chemical stimuli from six items including those from their natural and potential prey (fish, frog, lizard, mouse, water, and cologne) to newborn snakes. Significant effects of stimuli on the tongue-flick responses were detected. On the other hand, effects of population and interaction between stimuli and population were not significant, and individual comparisons revealed no significant interlocality differences in responses to either frog or lizard chemicals. Thus, our hypothesis was not supported. However, in the Mikura-jima sample, significantly fewer snakes responded to frog chemicals than in the main island sample. The significance of the inconsistency between prey recognition ability and prey availability in the Mikura-jima population are discussed. Received: October 17, 2000 / Accepted: December 14, 2000     

Response of fiddler crabs (Uca tangeri) to video playback in the field

The fiddler crab Uca tangeri communicates using a visual waving display and a vibratory drumming signal, both thought to function in mate attraction. Using video playback techniques, images of an empty mudflat, a waving male, a threatening male, and a wandering female were presented to male subjects. All stimuli elicited similar levels of low-intensity waving, but significantly more high-intensity waves were elicited by the female and threatening male stimuli than the mudflat stimulus or the waving male stimulus. This concurs with other research that the waving display is used at a higher intensity to attract females. The threatening male stimulus failed to elicit the same response as an actual threatening male and we discuss the likely reasons for this. The subjects also spent a significantly greater proportion of time drumming during the male waving stimulus than during the female stimulus, suggesting that drumming functions in male-male competition as well as female attraction. Received: 18 October 1999 / Received in revised form: 25 November 1999 / Accepted: 10 December 1999     

Computer-manipulated stimuli as a research tool in Mozambique tilapia <Emphasis Type="Italic">Oreochromis mossambicus</Emphasis>

Multimodal communication is essential in social interactions in cichlid fish, including conspecifics’ recognition, agonistic interactions and courtship behaviour. Computer-manipulated image stimuli and sound playback offer powerful tools to assess the relative relevance of visual and acoustic stimuli in fish behavioural studies, but these techniques require validation for each taxon. The aim of the present study was to investigate whether Mozambique tilapia Oreochromis mossambicus responds to computer-manipulated visual stimuli and acoustic playback. Six experiments were conducted: computer animation playback, video playback, interaction with a mirror, presentation of a live male in a jar alone and combined with courting sound playback or with white noise playback. Individual agonistic interactions (lateral displays, up and down swimming, butting) and courting behaviours (tilting leading, digging) were tallied for each experiment. Our results suggest that non-interactive computer-manipulated visual stimuli is not a suitable tool in behavioural research with Mozambique tilapia. In contrast, interaction with a live male in a jar seems to remain the best visual research instrument inducing significant strong behavioural responses. Although none or only a few agonistic interactions were observed towards video playbacks or computer animations, such interactions significantly increased towards a male in jar and were modulated by courtship sound playback, suggesting the additional relevance of sound playback as a tool in behavioural research with Mozambique tilapia, including the study of multimodal signalling.     

Computer-generated animal model stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In particular, understanding the constraints on visual signal design for communication has been of great interest. Traditional methods for investigating animal interactions have used basic observational techniques, staged encounters, or physical manipulation of morphology. Less intrusive methods have tried to simulate conspecifics using crude playback tools, such as mirrors, still images, or models. As technology has become more advanced, video playback has emerged as another tool in which to examine visual communication (Rosenthal, 2000). However, to move one step further, the application of computer-animation now allows researchers to specifically isolate critical components necessary to elicit social responses from conspecifics, and manipulate these features to control interactions. Here, I provide detail on how to create an animation using the Jacky dragon as a model, but this process may be adaptable for other species. In building the animation, I elected to use Lightwave 3D to alter object morphology, add texture, install bones, and provide comparable weight shading that prevents exaggerated movement. The animation is then matched to select motor patterns to replicate critical movement features. Finally, the sequence must rendered into an individual clip for presentation. Although there are other adaptable techniques, this particular method had been demonstrated to be effective in eliciting both conspicuous and social responses in staged interactions.     

《微生物工程》CAI课件的研制与教学实践

本文介绍了生物工程专业《微生物工程》课程CAI课件的设计、制作和应用效果评价。课件的设计力求课程知识体系完整、内容丰富、重点突出, 适当结合图片、动画和视频、音频效果的运用, 以达到激发学生的学习兴趣、提高教学效果的目的。重点介绍发酵参数检测与自动控制和发酵设备等课程核心内容。利用Powerpoint 软件进行课件制作, 利用Flash 4软件编制动画, 利用Adobe photoshop软件进行编辑扫描图, 并采用“课件大师”软件对已编好的章节进行统一管理。对2届学生的调查表明, 学生对此课件的满意度达到85%。     

Spontaneous Gating of Olfactory Cyclic-Nucleotide-Gated Channels

In vertebrates, cilia on the olfactory receptor neurons have a high density of cyclic-nucleotide-gated (CNG) channels. During transduction of odorous stimuli, cyclic AMP is formed. cAMP gates the CNG channels and this initiates the neuronal depolarization. Here it is shown that the ciliary CNG channels also open spontaneously. In the absence of odorants and second messengers, olfactory cilia have a small basal conductance to cations. Part of this conductance is similar to the cAMP-activated conductance in its sensitivity to channel inhibitors and divalent cations. The basal conductance may help to stabilize the neuronal membrane potential while limiting the sensitivity of odorant detection. Received: 30 May 2000/Revised: 8 August 2000     

Depth cues, behavioural context, and natural illumination: some potential limitations of video playback techniques

By expanding on issues raised by D’Eath (1998), I address in this article three aspects of vision that are difficult to reproduce in the video- and computer-generated images used in experiments, in which images of conspecifics or of predators are replayed to animals. The lack of depth cues derived from binocular stereopsis, from accommodation, and from motion parallax may be one of the reasons why animals do not respond to video displays in the same way as they do to real conspecifics or to predators. Part of the problem is the difficulty of reproducing the closed-loop nature of natural vision in video playback experiments. Every movement an animal makes has consequences for the pattern of stimulation on its retina and this ”optic flow” in turn carries information about both the animal’s own movement and about the three-dimensional structure of the environment. A further critical issue is the behavioural context that often determines what animals attend to but that may be difficult to induce or reproduce in an experimental setting. I illustrate this point by describing some visual behaviours in fiddler crabs, in which social and spatial context define which part of the visual field a crab attends to and which visual information is used to guide behaviour. I finally mention some aspects of natural illumination that may influence how animals perceive an object or a scene: shadows, specular reflections, and polarisation reflections. Received: 23 November 1999 / Received in revised form: 9 February 2000 / Accepted: 10 February 2000     

Extent of digging and its possible underlying causal factors in penned blue foxes

A recent European animal welfare recommendation stresses the importance of studying digging behaviour in farm-born blue foxes (Alopex lagopus). The current study was conducted (1) to clarify the extent of digging and (2) to evaluate factors that motivate digging. In experiment 1, six juvenile male blue foxes were housed together from August to the following June in an earthen enclosure. Experiment 2 was conducted from July to December, using ten enclosures each containing two juvenile male blue foxes. Behaviour was monitored by 24-h video recordings and visual observations. Progress of digging was also followed by making scale drawings of all digging marks on paper. As early as the first study day, clear signs of digging were observed. Digging sites were concentrated below and close to nestboxes and pen walls. Maximally about 20% of the total enclosure area was affected. The total surface area of digging sites did not increase from late summer onwards because foxes tended simultaneously to cover part of the old sites when digging new ones. Motivational tendency to dig varied with time. Digging activity decreased during autumn and almost totally ceased during winter. In May, foxes resumed digging activity. Digging motivation was evaluated by two means: (1) by analyzing digging purpose (experiments 1 and 2), and (2) by the damming-up test (experiment 1), that is, after 10 months foxes that had been exposed to the earthen floor were transferred for 12 days into wire-mesh cages with no possibility to dig in the ground. Thereafter, foxes were transferred back into the earthen enclosure to measure the rebound of digging following deprivation. Foxes were observed to dig for the following reasons: (1) to make a hole or a resting site, (2) to locate an escape route, (3) to cache food, faeces, or sticks, (4) in response to a novel object (new nestbox, replacement of nestbox), and (5) displacement without any clear goal. Daily time spent digging averaged 7 min and 17 min per fox in Exps. 1 and 2, respectively. A clear rebound effect for digging was not identified. It can be concluded that digging is a complex behavioural pattern caused by a variety of motivations that can vary over time. The present study was unable to show unambiguously that digging is an important need for farmed foxes. Received: 28 February 2000 / Received in revised form: 6 June 2000 / Accepted: 20 June 2000     

Aqueous two-phase: the system of choice for extractive fermentation

Extractive fermentation in aqueous two-phase systems is a meaningful approach to overcome low product yield in a conventional fermentation process, and by proper design of the two-phase system it is possible to obtain the product in a cell-free stream. The characteristics of an aqueous two-phase system, various polymers used for forming an aqueous two-phase system, the physicochemical parameters of the aqueous two-phase system, partitioning of biomolecules and cell mass and the effect of individual phase forming polymers on cell growth and product formation are reviewed in this article. The various extractive fermentation processes are also summarised here. At the end, the economic viability and scope of aqueous two-phase fermentation are briefly discussed in relation to the wider application of this topic. Received: 16 June 1999 / Received revision: 29 December 1999 / Accepted: 4 January 2000     

Wavelet entropy in event-related potentials: a new method shows ordering of EEG oscillations

 In this work we show the application of a measure of entropy defined from the wavelet transform, namely the wavelet entropy (WS), to the study of event-related potentials (ERPs). WS was computed for ERPs recorded from nine healthy subjects with three different types of stimuli, among them target stimuli in a cognitive task. A significant decrease of entropy was correlated with the responses to target stimuli (P300), thus showing that these responses correspond to a more “ordered” state than the spontaneous EEG. Furthermore, we propose the WS as a quantitative measure for such transitions between EEG (“disordered state”) and ERP (“ordered state”). Received: 12 April 2000 / Accepted in revised form: 11 September 2000     

Investigation on the induction of 14-3-3 in white spruce

 A cDNA encoding a 14-3-3 protein was isolated from white spruce. The corresponding polypeptide contains several motifs that are conserved in this type of protein and is predicted to be 260 amino acids in length. Multiple banding in Southern blot analysis suggests that the gene encoding this cDNA is, in fact, part of a small family of genes. Wounding and chitosan treatment of spruce plants followed by Northern blot analysis indicates that these stimuli caused the accumulation of 14-3-3 mRNA. In addition, cell suspension cultures treated with methyl jasmonate showed up-regulation of 14-3-3-encoding mRNA. Chitosan and methyl jasmonate are both signalling molecules in the activation of plant defense response genes. Therefore, our results suggest a possible role for this 14-3-3 protein in the pathogen defense response of coniferous trees. Received: 13 December 1999 / Revision received: 21 August 2000 / Accepted: 22 August 2000     

An edited linkage map for the AXB and BXA recombinant inbred mouse strains

We have updated the history of the AXB and BXA recombinant inbred (RI) strains, typed additional loci, and edited the AXB, BXA RI database. Thirteen of the original 51 AXB and BXA RI strains are either extinct or genetically contaminated, leaving 33 living strains available from The Jackson Laboratory. However, we found a high degree of similarity among three sets of strains, indicating that these strains are not independent, which leaves 27 independent RI strains in the set. Accordingly, we modified the database by combining the AXB and BXA RI sets and eliminating strains that were genetically contaminated or extinct with no available DNA. We added 92 newly typed loci, retyped some questionable genotypings, and removed loci with excessive double crossovers or an insufficient number of typed strains. The edited strain distribution pattern (SDP) is available on the World Wide Web (WWW) (http://www.informatics.jax.org/riset.html) and now includes over 700 loci. Each locus is linked to adjacent loci with a LOD score of at least 3.0 with a few described exceptions. We also carried out a second editing designed for the analysis of quantitative trait loci by deleting extinct strains and loci with identical SDPs; this edited database is also available on the WWW. Received: 20 March 1998 / Accepted: 26 May 1998