Het testen van visuele gevoeligheid voor de snelheid en richting van de beweging in Lizards

Hi, I'm Kevin Wu from the Center for the Integrative Study of Animal Behavior at Macquarie University here in Sydney, Australia. In this video-based article, I'm gonna be talking about testing motion sensitivity and lizards. And when I talk about testing motion sensitivity, I'm talking about using an operating conditioning paradigm.

And when I'm talking about upper and conditioning, that's when you take a subject animal participant or human and teach them the characteristics about an object in which they hope to learn and respond to appropriately when the object is presented and hopes to get reinforced for that response. Now, offering conditioning generally allows us to understand two things. One, it allows us to understand a learning and memory sensor or capacity, and two, it allows us to understand the sensory capacity of that particular individual or species.

Now testing motion sensitivity and learning and memory and lizards has been quite difficult in so much that there are particular parameters that have been difficult to uncover. One is that lizards are notoriously difficult in establishing a particular motivational system as well as finding the right reinforcement in which to keep them interested at the tasks at hand here we're going to use the Jackie Lizard as a model species in which to test both learning and memory and especially motion sensitivity. Jackie lizards are a native, a gammut species to Australia that are highly cryptic but active during the day, but can be characterized by highly stereotype visual displays that are used for social communication.

And I see visual displays that make this particular species quite visual. So what we're going to demonstrate at this video is that not only can Jackie Dragons learn and it can remember certain things, but they have quite a high level of sensitivity. In addition, I hope to demonstrate that Jackie Liz can also be used for or as a model species for other Particular tasks.

As Seen before, random grams are highly saline and engaging the visual system. They do not engage recognition, they do not resemble anything biologically meaningful and there are classic psychophysics technique in both human and animal perception. And when we talk about psychophysics, we're really talking about understanding the characteristics or properties about a sound or an object.

Responses by an animal subject or participant allow us to understand which thresholds that these particular characteristics are either heard or seen, and this gives us an understanding into the sensory perception of these organisms. Here's an example of what VPX can do. In this example, we have an inner circle with dots coming towards the foreground, but in the background we have random dots.

V PPIC X allows you to create a series of different illusions in which to test different characteristics of sensory perception. In addition to these characteristics, it allows us to control things such as coherence, which is the direction of movement and also the speed of these dots. Final Cut Pro is a video editing program available from Apple.

There are three main parts of final Cut Pro. On the canvas is where you view your sequence as it's being built. The timeline is where you place each part of the sequence or each segment and can view it as it is, as it says on a timeline, and the bin allows for multiple storage of sequences or the sequences to be put in the timeline.

All dot sequences are completed using Final Cut Pro. All sequences initially designed in VIX are imported into the bin. On the canvas view you can see an example of the dots being formulated.

However, all dots are constructed using the timeline. So here you can see our example shows 2.5 seconds of 0%coherence initially followed by five seconds of the variable stimulus, and then finally 7.5 seconds of a hundred percent coherence. You'll now see examples of varying dot speed and dot coherence.

Speed again is measured in degrees per second, and coherence is the percentage of dots moving in either the left or right direction. This Is an example of a completed dot sequence. All the dots here are moving at 10 degrees per second.

Initially 2.5 seconds are shown with 0%coherence. In this example at the variable stage, 40%of the dots will be moving the left direction for the next five seconds. This will then be followed by 7.5 seconds of a hundred percent coherence going in the left direction.

The total sequence is 15 seconds. Our setup consisted of three video playback rigs. On the central monitor is where the random dot kin monograms were displayed.

On the adjacent monitors is where the secondary reinforces would be displayed once the subject is made a correct choice. The IMAX seen here on the right hand side stored all the video clips on the displays. The camera, which was situated above the testing arena was videotaped and recorded and seen on a viewfinder and VCR.

All digital sequences were converted from analog using a cannabis box. Secondary Reinforces were created using LightWave layout version 8.3. LightWave is a 3D animation tool that allows us to build scenes in which these animations are created.

There are two particular features of light wave layout. First is a camera and where the object can be seen, second is light and these light or lights will illuminate the area in which the object is seen. We selected three animated invertebrates to use as a secondary reinforces.

These were cricket, mite and spider. These invertebrates were quite similar to what these subjects would see out in the wild. The movements of these invertebrates were also mimicked off of realistic movements, videotaped and recorded using a digital camcorder.

This Is Our basic testing setup. The red circle identifies our subject.Initially. The subject will say 2.5 seconds of 0%coherence on the screen in front of him.

After 2.5 seconds of 0%coherence, the subject will be shown five seconds in which dot speed and coherence will vary. It is within this five second critical period that the subjects supposed to select either the left or right monitor. Based on variations in these visual characteristics, the ability to select the correct monitor provides us with an understanding of their sensory capacity.

In this example, subjects are expected to go to the left monitor as the dots are going at a hundred percent. During This period, the subject is then expected to use the information acquired from the moving dots and move to the left monitor. Within the five second critical period, our subject should select the appropriate monitor.

In this case it should be the left monitor. Then at 7.5 seconds, if the subject has selected the appropriate monitor, it will be presented with a secondary reinforcer and in this case, our secondary reinforcer is a cyber invertebrate. In the next section, you'll then see the completion of what an actual trial looks like.

Early attempts to Establish this a reliable procedure were highly unsuccessful and there are a few reasons for this. First, there were no primary reinforces. Secondly, instead of cyber invertebrates, lizard footage displaying social displays were used as a secondary enforcer.

And thirdly, that the length of each trial was too long. Each of these particular factors prevented the subjects from actually acquiring contingency and in fact increased aversive displays between the subjects themselves. I believe that are these factors that were now eliminated and if not modified, that therefore prevented from subjects from acquiring the contingency.

Now we have established a successful procedure and this has largely been a trial and error process, and although Liz is are notorious for being quite difficult in establishing particular opera procedures, this method has been successful and quite reliable. So not only can we study visual communication and visual sensitivity and Jackie lizards, but quite possibly we can apply this methodology to other lizards and other species in so much. We can also apply this methodology to other aspects of vision.

We can also apply to other sensory modalities such as audition chemoreception and tactile perception.