Polarization Vision—Overcoming Challenges of Working with a Property of Light We Barely See

Abstract

In recent years, the study of polarization vision in animals has seen numerous breakthroughs, not just in terms of what is known about the function of this sensory ability, but also in the experimental methods by which polarization can be controlled, presented and measured. Once thought to be limited to only a few animal species, polarization sensitivity is now known to be widespread across many taxonomic groups, and advances in experimental techniques are, in part, responsible for these discoveries. Nevertheless, its study remains challenging, perhaps because of our own poor sensitivity to the polarization of light, but equally as a result of the slow spread of new practices and methodological innovations within the field. In this review, we introduce the most important steps in designing and calibrating polarized stimuli, within the broader context of areas of current research and the applications of new techniques to key questions. Our aim is to provide a constructive guide to help researchers, particularly those with no background in the physics of polarization, to design robust experiments that are free from confounding factors.

Computational simulation of human perception of spatially dependent patterns modulated by degree and angle of linear polarization

“…As described previously [20], theory was tested in an optical model in which an LCD-generated polarization-modulated pattern was photographed through a polarizing filter with diattenuation that was radially symmetric about the centre point of the filter (Oriel Instruments, 'Polarization axis finder' 25328). The method was extended here to two types of LCD: a twisted nematic (TN) LCD (Dell P1913Sb) for the generation of an AoP stimulus, and an in-plane switching (IPS) LCD (Dell P1914Sc) for the generation of a DoP stimulus [11]. Each of the monitors was converted into a polarizationmodulated display by the removal of the front polarizing filter [7,21,22] and insertion of a blue-transmitting polymer filter (Lee Filters Ltd, UK, #075, 'evening blue'; peak transmission 440-460 nm) behind the back polarizing filter of the LCD panel [6,20].…”

“…The luminance output of each monitor was the same, as determined using a photometer (model CS100-A, Minolta Co. Ltd., Japan,); similarly, the spectral output of each monitor was identical, as determined using a solid-state spectrometer (USB2000, Ocean Optics Inc., FL, USA). The polarization output of the monitors was calibrated as previously described [6,11]. Densitometry of digital images was performed with image analysis software (Image J [23]).…”

“…The present study extends our previous work to include patterned linear polarization fields and degree of polarization. In so doing, we are able to simulate the visual perception of patterned linearly polarized stimuli modulated either by degree or angle of polarization, scenarios that can be generated using liquid crystal display (LCD) technology [11]. Predictions arising from the model are tested using an optical model and in vivo measures on normally-sighted human participants.…”

Parallel processing of polarization and intensity information in fiddler crab vision

“…Stimuli were presented to crabs using a custom-built intensitypolarization (IP) screen that allowed intensity and polarization contrasts to be adjusted independently. The screen consisted of two displays that were spatially and temporally synchronized: (i) a digital projector (CP-WX3030WN, Hitachi Ltd., Tokyo, Japan) that cast an intensity-based image onto a sheet of diffuser (#250 Half White Diffusion, Lee Filter, Andover, UK) on the rear surface of (ii) a modified patterned vertical alignment type LCD panel dissembled from its outer casing (1905FP, Dell, Round Rock, USA) and with the outermost polarizer removed (40). The IP screen thus allowed the degree of polarization and the intensity of an image to be controlled simultaneously and independently (Fig.…”

Investigating Defensive Colouration in Nudibranch Molluscs using a Novel Analytical Framework for the Study of Animal Colour Patterns​​​​​​​

“…Endler et al, 2018), given recent advances in the understanding of colour pattern functionality in the context of motion (Fleishman, 1986;Hughes, Troscianko, & Stevens, 2014;Ramos & Peters, 2017;Murali, 2018;Nityananda et al, 2018;Umeton, Tarawneh, Fezza, Read, & Rowe, 2019). There are types of visual information we have barely begun understanding, such as polarisation vision, the use of fluorescence as well as their interaction with an animal's perception of colour and brightness (Foster et al, 2017;Marshall & Johnsen, 2017;Marshall et al, 2018;Smithers, Roberts, & How, 2019).…”