Recently, I attended a lecture given by Dr. Kevin Woo of the psychology department. The lecture was entitled Sensitivity to Salient Movement: The Motion Characteristics on Signal Design in the Jacky Dragon. The Jacky Dragon is an Australian agamid lizard. Their habitats include sclerophyll forest, rocky ridges and costal heathland. Jacky dragons perform stereotypical visual displays in the form of social signals. There are three normal social signals that are displayed the tail-flick is an alert signal, a push-up body rock is an aggressive signal, and the slow arm wave is a submissive signal. They also have a receiver sensory system. In this receiver sensory system, specific sensory receivers are engaged by specific signals. They exploit preexisting biases and are used to understand sensory and perceptual phena. There are four components to the receiver sensory system. The first two conspicuous and stimulate receiver organs are classified as sensory. Predictable and memorable are cognitive compounds.
Researchers need four things to understand motion perception. They need to be able to quantify motion perception. They need to be able to test sensitivity to movement. They need to understand basic sensory processes. Finally, they need to be able to identify correlations between visual sensitivity and movement.
The study that was conducted to test motion perception first trained the Jacky dragons instrumentally. Dot kinematograms, which do not resemble biologically meaningful stimuli, were used. The dots on the computer screen moved randomly until the experiment was started. For the experiment, the dots would move in one direction at a specific coherence, the percentage of dots moving in that direction, at a specific speed, either 5, 20, or 80 degrees per second. 128 conditions were tested. After the computer displayed the dots, the dragons would move to the side in which the dots were moving. When the dragons moved to the correct side, they received a reward of a cyber invertebrate. The results found that the dragons are sensitive to high speed movement and have difficulty in perceiving slow-moving targets. Next they placed the dot kinematograms on the backdrop of a natural setting. The natural settings included still, calm, and windy settings. In this study, the results indicated that increase of wind mask speeds that are low and the dragon’s capacity to discriminate the stimuli.
In another experiment with the Jacky dragons, a computer animated dragon was created on the computer. The programs created identical movements to the social signals displayed in the dragons. This experiment stimulated competition of isolated motor patterns across natural wind conditions. The results found the tail flick was the highest on the hierarchy of conspicuousness, followed by the push-up body rock and finally the slow arm wave. The slow arm wave is a submissive behavior so it is predictable that it would be on the lower end of the hierarchy. The results indicate that Jacky dragons are highly sensitive to fast motion. They have different sensitivity to aggressive and submissive signals. They are stable across natural wind conditions. They match displays to changing wind conditions. They can discriminate between morphological cues.
I greatly enjoyed the lecture. I liked the process in which Dr. Woo went about to learn how the dragons perceived objects and motion. I think it is hard as humans to think that other animals see the world differently then we do. It is difficult to put yourself in another’s’ eyes to see how they see things. I wonder what other research has been done with other animals that is similar to this.
Thursday, March 5, 2009
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