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Department of Physiology, Development and Neuroscience

 

Director of Studies in Medicine and Veterinary Medicine, Newnham College
Tel: +44 (0)1223 334057, Fax: +44 (0)1223 333840, E-mail: ajm41@cam.ac.uk

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Sheep  in the testing system.

The sheep enters the ambulatory circuit through a gate at the beginning of the entering corridor that is opened by the handler. Walking along the corridor, the sheep activates an infra-red sensor to initiate the trial. Upon trial initiation, an auditory starting signal is presented via speakers and stimuli are presented on the computer screens that are integrated into the wall of the operant system. In order to select one stimulus, the sheep breaks an infrared beam above the feed trough below the relevant screen. A food reward is delivered into the trough (for a correct response). The delivery of the food (or an auditory error signal for an incorrect selection) indicates the end of the trial. The sheep then proceeds through a one-way gate back to the entering corridor and initiates the next trial.

Training 1-3

This video was made for demonstration purposes and was not part of the original training. The video shows examples of the sheep’s choice of the correct stimuli during each training stage. Example stimuli are identical to those used during the training.

Recognising learned and very familiar faces

This video was made for demonstration purposes and was not part of the original training. The video shows first an example of a sheep’s choices during the probe test where the sheep has to chose the picture of the celebrity in all different persectives, and then the selection of the very familiar face (handler).

The first time seeing a photo of her handler

The video clip in this sequence was part of the original experiment. In this trial, the sheep sees a 2D image of the handler for the first time. The handler’s photo is on the left, the unfamiliar face is on the right. (A different handler is running the session.) This sheep has already learned to perform the task using the faces of celebrities, so she is expecting to see two faces on the screens (one learned familiar, one unfamiliar). The sheep approaches the screens - sees the photo of the unfamiliar face, and expects therefore the other photograph to be one of the familiar faces (celebrity) that she has learned. (We intermixed the handler’s face amongst the celebrity faces that they had learned to recognize.) Note her reaction when she sees a picture of her handler. She double checks the stranger face, and then, after a pause, choses the handler's photograph.

A mouse performs in the two-choice discrimination task
Stimuli are presented on the touchscreen in pairs, one the correct S+ and the other the incorrect S-.

A nose poke to the S+ results in a tone and the onset of a light in the food hopper accompanied by delivery of a reward pellet. Incorrect responses are followed by a correction procedure, where the house light is extinguished for 5 seconds. Both discriminative stimuli are presented an equal number of times during a session. The left-right arrangement is determined pseudorandomly, with a constraint that a given stimulus cannot appear on the same side of the screen on more than 3 consecutive trials.

Gerty performs in the two-choice discrimination task

This video was not part of an actual experiment. It was shot the day after Gerty had learned to do this discrimination (i.e. she had reached criterion).

Gerty has learned that if she chooses the side withthe ‘x’, there will be a reward (a few sheep nuts) in the bucket. Sometimes she makes her decision very quickly, other times (e.g. choice number 3) you can see that she appears to be comparing the symbols quite deliberately.

Gerty procedes through the task at her own pace. Note that she shows some behaviours in the video that are not typically seen during the task. This is because she had never done the task in the presence of a second person before. For example, she checks with the operator on some of the discriminations when she sees the person operating the video camera (who is not usually there). However, she does not gain information about the correct choice from the operator. Until the sheep has made her choice, the operator remains near the previous exit gate, with her back turned so the sheep cannot see her face.

Gerty got 100% correct in this run.

Gerty is a two year old Welsh mountain ewe. She was named after Gerty Cori, who won a Nobel Prize in Physiology or Medicine in 1947, for the discovery of the course of catalytic conversion of glycogen.

Roslyn fixates on her self-image

Roslyn spends long periods of time fixating on her self-image either with both eyes (binocular) or with one eye (monocular).

Self-fixation. The sheep spends long periods of time fixating on the self-image either with both eyes (binocular) or laterally with one eye (monocular).

Two sheep looking at each other via the mirror

Doris fixates on the mirror image of Roslyn and then appears to check this against the real image of Roslyn beside her. Both sheep have been flock member for the last 4 years.

Visual Comparison using the mirror. The sheep first fixates on the mirror image of the other sheep within the testing area and then looks to the real animal.

Gerty investigates behind the mirror.

After following the self-image across the length of the mirror, Gerty attempts to investigate behind the mirror.


Investigating behind the mirror. After following the self-image across the length of the mirror, the sheep attempts to investigate behind the mirror.

Gerty demonstrates signs of contingency behaviour

Gerty demonstrates signs of contingency behaviour whereby she moves her head or body in front of the mirror whilst monitoring the subsequent movements made by the self-image.

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Contingency behaviour. The sheep demonstrates signs of contingency behaviour whereby it moves its head or body in front of the mirror whilst monitoring the subsequent movements made by the self-image.