Engineering data compendium. Human perception and performance. User's guide

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

Colour Vision in Birds : Comparing behavioural thresholds and model predictions

Birds use colour vision for many biologically relevant behaviours such as foraging and mate choice. Bird colour vision is mediated by four types of single cones, giving them an extra dimension of colour information compared to trichromatic humans. The cone photoreceptors of birds have coloured oil droplets that are assumed to increase the discriminability of colours in bright light at the cost of dim light sensitivity. In this thesis I present four studies where we have trained chickens to perform colour discrimination and tested the limits of their behavioural performance. In paper I we tested how small colour differences chickens can discriminate. This allowed us to test the predictions of the most well established model for bird colour vision, the receptor noise limited model. There was a reasonably good fit between model and behaviour. Furthermore, we tested in how dim light chickens could discriminate colours and found that the intensity threshold was affected by the colour difference between the stimuli and their intensity. In Paper II we continued testing colour discrimination in dim light and tested the hypothesis that chickens sum the signals from many photoreceptors to increase contrast sensitivity at the cost of spatial resolution in dim light, so called spatial pooling. We used food containers covered with larger, smaller, more or fewer colour patches. Supporting the hypothesis, the containers covered by more colour could be discriminated in dimmer light. In Paper III we tested colour constancy, the ability to maintain colour perception in different spectral illuminations that would otherwise confuse colour perception. Our aim was to find the largest illumination change that chicken colour constancy could tolerate. We found that chicken colour constancy could tolerate larger illumination changes when discriminating stimuli that were more different from each other. In paper IV we continued the work on colour constancy but allowed the chickens to use relative colour learning, which was specifically excluded in paper III. In Paper IV we found that their colour constancy could tolerate larger illumination changes. In nature relative colour cues are available and may be an important aspect of colour learning and perception. These results suggest that such cues can make colour constancy more robust to larger illumination changes. In both experiments chicken colour constancy was improved if they were adapted for 5 minutes in the tested illumination before performing the discrimination task. We compared the illuminations for which chickens retained colour constancy, to the difference between natural illuminations and we can conclude that chickens are well equipped to maintain accurate colour perception when changing between habitats in the wild. Objects are detected both by their chromatic and achromatic contrasts. The receptor noise limited model can be used to predict discriminability through both chromatic and achromatic vision. To use the model reliably its assumptions and predictions must be compared to behavioural results. This has been done for the chromatic version of the model but not the achromatic. In Paper V we compiled all known chromatic and achromatic contrast detection thresholds, and used them to derive the limiting noise level to be used when predicting visual discrimination in a range of animals. We discuss the limitations of using modelling in the wild such as the need to consider the spatial pattern of the stimuli and the light intensities in which the modelling occurs

Luminance cues constrain chromatic blur discrimination in natural scene stimuli

Introducing blur into the color components of a natural scene has very little effect on its percept, whereas blur introduced into the luminance component is very noticeable. Here we quantify the dominance of luminance information in blur detection and examine a number of potential causes. We show that the interaction between chromatic and luminance information is not explained by reduced acuity or spatial resolution limitations for chromatic cues, the effective contrast of the luminance cue, or chromatic and achromatic statistical regularities in the images. Regardless of the quality of chromatic information, the visual system gives primacy to luminance signals when determining edge location. In natural viewing, luminance information appears to be specialized for detecting object boundaries while chromatic information may be used to determine surface properties

Mechanisms, functions and ecology of colour vision in the honeybee.

notes: PMCID: PMC4035557types: Journal Article© The Author(s) 2014.This is an open access article that is freely available in ORE or from Springerlink.com. Please cite the published version available at: http://link.springer.com/article/10.1007%2Fs00359-014-0915-1Research in the honeybee has laid the foundations for our understanding of insect colour vision. The trichromatic colour vision of honeybees shares fundamental properties with primate and human colour perception, such as colour constancy, colour opponency, segregation of colour and brightness coding. Laborious efforts to reconstruct the colour vision pathway in the honeybee have provided detailed descriptions of neural connectivity and the properties of photoreceptors and interneurons in the optic lobes of the bee brain. The modelling of colour perception advanced with the establishment of colour discrimination models that were based on experimental data, the Colour-Opponent Coding and Receptor Noise-Limited models, which are important tools for the quantitative assessment of bee colour vision and colour-guided behaviours. Major insights into the visual ecology of bees have been gained combining behavioural experiments and quantitative modelling, and asking how bee vision has influenced the evolution of flower colours and patterns. Recently research has focussed on the discrimination and categorisation of coloured patterns, colourful scenes and various other groupings of coloured stimuli, highlighting the bees' behavioural flexibility. The identification of perceptual mechanisms remains of fundamental importance for the interpretation of their learning strategies and performance in diverse experimental tasks.Biotechnology and Biological Sciences Research Council (BBSRC

Chromatic noise perception in digital photography

A model was built to predict chromatic noise perception in digital photography. The model includes the orthogonal opponent color space Y C1C2, and sets of optimized contrast sensitivity functions. Past research on opponent colors, contrast sensitivity functions at threshold and suprathreshold matching has been reviewed. Some historical opponent color spaces have been investigated in terms of transformation and application. Three psychophysical experiments were performed to build the model. Through the equi-luminance plane experiment three equi-luminance planes corresponding to three luminance levels were determined. Method of adjustment was applied for subjects to adjust chromatic noise image until it is least perceptible. Based on results from the first experiment, the orthogonal opponent color space Y C1C2 was developed. The Y C1C2 space shows optimal performance compared with OPP space, with the respect of separating luminance information from chromatic channels and vice versa. The threshold experiment measured contrast threshold for the three cardinal axes and the two diagonal axes of the new opponent color space with three frequency bands and three luminance levels. The QUEST procedure was applied for observers to choose which one of the two side-by-side-displayed stimuli has noise. The supra-threshold experiment was to measure contrast sensitivity above threshold. Method of adjustment was used for observers to adjust the noise contrast of the test stimuli to match the contrast of the parallel displayed achromatic anchor stimuli, which had three times threshold contrast. Sets of optimized CSFs were obtained by empirical modeling on experiment data from the threshold and supra-threshold experiments. The five-parameter band-pass CSF was fitted to model achromatic noise. As to chromatic noise, the six-parameter low-pass CSF was optimized to model chromatic noise. The fact that threshold CSFs and suprathreshold CSFs have similar shape suggests one set of CSFs may be applicable for both cases

Cortical simple cells can extract achromatic information from the multiplexed chromatic and achromatic signals in the parvocellular pathway

AbstractP cells, which carry both achromatic and chromatic information, are largely responsible for achromatic acuity and contrast sensitivity. The P cell achromatic information must be separated from the chromatic information to be useful. Cortical simple cells are well suited to the extraction of achromatic information by spatial bandpass filtering. Bandpass filtering of Type I P cells by cortical simple cells yields an achromatic signal with a residual chromatic response. The bandpass model makes predictions in accord with existing physiological data and explains the role of a heretofore puzzling class of cortical cells, which have bandpass tuning for both achromatic and chromatic modulations. The model is shown to be related to a previously postulated class of ideal detectors. Finally, the model is used to make a number of physiological and psychophysical predictions

Hoverflies are imperfect mimics of wasp colouration

Many Batesian mimics are considered to be inaccurate copies of their models, including a number of hoverfly species which appear to be poor mimics of bees and wasps. This inaccuracy is surprising since more similar mimics are expected to deceive predators more frequently and therefore have greater survival. One suggested explanation is that mimics which appear inaccurate to human eyes may be perceived differently by birds, the probable agents of selection. For example, if patterns contain an ultra-violet (UV) component, this would be visible to birds but overlooked by humans. So far, indirect comparisons have been made using human and bird responses to mimetic stimuli, but direct colour measurements of mimetic hoverflies are lacking. We took spectral readings from a wide range of hoverfly and wasp patterns. They show very low reflectance in the UV range, and do not display any human-invisible colour boundaries. We modelled how the recorded spectra would be perceived by both birds and humans. While colour differences between wasps and hoverflies are slightly more distinct according to human visual abilities, bird vision is capable of discriminating the two taxa in almost all cases. We discuss a number of factors that might make the discrimination task more challenging for a predator in the field, which could explain the apparent lack of selection for accurate colour mimicry