NRSA Fellowship for Singer: Value of Rewards after Relatively Aversive Events

I had many opportunities to become involved in animal behavior research prior to my entry into graduate school. Shortly after graduation, I accepted a position at Kewalo Basin Marine Mammal Laboratory, a division of the University of Hawaii. Under the direction of Dr. Louis Herman, I assisted with a project that investigated the ability of bottlenose dolphins to perform a matching to sample task using two modalities: vision and echolocation. Dolphins were able to correctly match an item previously explored visually to an item that had to be chosen from three alternatives that could only be sensed echoically. Similar results were found when the dolphin first echolocated on an object, then had to choose among three objects explored visually. These results indicate that dolphins can match across modalities. As a research assistant on the Giant Panda Project at Zoo Atlanta, I investigated the effects of early rearing experience on reproductive success in giant pandas. I performed behavioral observations on cubs with and without a mother as well as older pandas that had been raised in both conditions. In addition, I investigated the feasibility of raising panda cubs with a surrogate panda mother. Results indicated that early rearing experiences were especially important for male cubs. There seemed to be no adverse effects to cubs raised with a surrogate, rather than birth, mother. The results of this experiment have been published. My graduate research experience began in Dr. Thomas Zentall's laboratory at the University of Kentucky. I began my work in his lab looking at how pigeons code long (1 O-sec) versus short (2-sec and O-sec) samples over increasing delays. Spetch and Wilke (1983) have hypothesized that over time, the memory for longer samples becomes subjectively shorter. So, over long delays, a IO-sec sample appears more like a 2-sec sample and a 2-sec sample appears to be more like a O-sec sample. However, in a series of studies, we were able to show that pigeons confuse the intertrial interval (ITI) with the novel test delays and are thus biased to respond to samples as if they were absent (e.g. short). When the IT! and the delay are made distinct (by lighting the IT! and the delays remaining dark), the subjective shortening effect disappeared. The results of these studies have recently been published. I am now involved in a study that exams the effect of stimulus salience on pigeon's ability to time. It is possible that if the sample stimulus is not salient enough, the pigeons begin to time from when the lit III ends until the time when the comparisons appear, rather than just timing the presence of the stimulus. This experiment is still in progress. My thesis experiment investigated the ability of rats to use cognitive maps to navigate a three-arm maze. A cognitive map is an internal representation of the spatial relationship of objects within an animal's environment. To demonstrate that cognitive mapping is the mechanism being used, a researcher must rule out the use of other mechanisms, such as landmark use, to guide navigation. Previous research in our lab showed that rats were unable to choose an alternative route to food when intramaze and extramaze cues had been eliminated from the maze. I believed that landmarks were necessary for the formation of internal maps of the environment, so I incorporated intramaze cues into the training phase of the experiment. Rats were then able to choose a novel shortcut to a familiar reward location based on remembered spatial location information. A manuscript describing this research has recently been submitted for publication. I am currently working on a study investigating episodic-like memory in pigeons. Episodic memory is the memory for personal events, and usually involves information about what the event was, where the event took place, and when the event occurred. A key element in the current study of episodic memory is how the use of an "unexpected question" to ask about what, when, or where is important to the task. In this experiment, pigeons are first trained to report whether they pecked at a left or right spatial location. Next, pigeons are given experience pecking left or right in an arbitrary matching to sample task. During the testing phase, pigeons are given probe test trials in which matching to sample trials are not followed by food (as expected) but the simultaneous discrimination they used previously to report whether they had pecked to the left or right. This allows us to ask pigeons whether the question "where" at a time when the subject does not expect to be asked about spatial location and can therefore, not learn a rule for answering the question. This study is still in progress.