# Bird eyes - and how to model them!

by Samuels-art
Tags: bird, discrimination model, eyes, jnds, model, modelling or theory, visual perception, weber fraction
P: 18
OK so I am not sure if this should be on a physics forum, a maths forum or a biology forum. All I know is I am stuck.

A little back ground: Researchers have modelled how various animals can see depending on their visual sensor cells, namely cones (colours vision) and rods (luminance).

What I understand is that I am supposed to use my light spectrophotometer reflectance data and run a discrimination model to get JNDs (Just Noticeable Differences), the measurements used to discriminate weather or not a bird can tell the difference between either colours (using the models used for comes) or luminance (rod models). This is usually based on a discrimination factor (often Weber fraction 0.05), and relative proportions of vision cone types in predator's retina. The results from discrimination model are JND's.

As far as I understand Vorobyev & Osorio 1998, Osorio & Vorobyev 2005 (Attached :)) are probably the most influential papers defining foundations of vision modelling. But seriously, having read them through approximately 4 or 5 times over the last 3 weeks I am no further forward in actually opening excel (or the software needed) and actually making a model. I don't even know if 'running a model' is metaphoric or I need to open R or similar and run something!!!

Any help would be greatly appreciated.

Kind Regards

Sam
Attached Files
 Receptor noise as a determinant of colour thresholds.pdf (293.8 KB, 4 views) Colour thresholds and receptor noise behaviour and physiology.pdf (263.1 KB, 2 views)
 Homework Sci Advisor HW Helper Thanks ∞ PF Gold P: 11,114 Start with the end in mind: what is your model supposed to be telling you? What will it be useful for - specifically? What is your level of physics and math here? Note: excell is unlikely be up to the task.
 P: 18 The model is supposed to tell me what the JNDs are for my two treatments, from this I can tell if a bird can discriminate between two visual signals. It will be and has been used for putting spectrophotometer data into an ecologically relative context. My personal level? not great but I need to complete this analysis so I really have no choice but to figure it out. I know people who are less mathematically literate than I am have completed this analysis and I am finding it incredibly frustrating. Equations scare, I will not lie. I do however want to learn how to solve them..and not be scared any more!!
P: 18

## Bird eyes - and how to model them!

Point taken on excel!!
 Homework Sci Advisor HW Helper Thanks ∞ PF Gold P: 11,114 Have you done this kind of modelling before - say for different sorts of eyes? i.e. what is the holdup? Where do you get stuck?
 P: 18 Hi, No, I have not done this before or anything like it. I do not have a clue where to start! I have my Photospec. data that is it. I just don't get the concept of running a model or where to get the numbers to put into an said model. Just imagine someone with zero confidence in maths and equations. But with a health, almost unhealthy appetite to learn!
 Mentor P: 39,722 Is this for some kind of research project? What is the end goal? How did you end up with this project, if you don't have the modeling experience yet?
 P: 18 Fair question! I am a PhD. student learning my trade so to speak! I guess as in all research, the end goal is to publish! I am a biologist, working with iridescent insects (see some other posts). I would like to model my light spectro. data with their potential predators! i.e. birds and specifically bluetits as most research on avian visual modelling has been done with this species. I was not being vague on purpose, I just didn't think the information was needed. Apologies, I have no mysterious motives. Kind Regards S.
 Homework Sci Advisor HW Helper Thanks ∞ PF Gold P: 11,114 So you know how eyes work and you have some standard model for rods and cones? iirc different species of bird have different vision characteristics.
 P: 18 Yes, there is a standard model for blue tits (and various other species) for both rods and cones. The birds have 4 cone types, as ours plus U.V. sensitive. The models are in the attached papers!
 Homework Sci Advisor HW Helper Thanks ∞ PF Gold P: 11,114 So what's the problem?
 P: 18 How do I implement the (any) model? Where do I start to understand it enough to get out what I want? What is a discrimination model?