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Chapter 11

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Anneke Olthof

1 Chapter 11: - Exploring cognitive skills of animals tells us about the uniqueness of various human cognitive skills What is Comparative Cognition? - Commonly referred to as through processes - Thinking is regarded as voluntary, deliberate and conscious reflection on some topic, usually involving language. - Comparative cognition can lead to actions that cannot be explained on the basis of the external stimuli. - Cognitive Ethology: claim that animals are capable of conscious thought and intentionality. - The claim that nonhuman animals are capable of consciousness and intentionality is based on the complexity, flexibility, and cleverness of various examples of animal behaviour. - Comparative cognition does not imply anything about awareness, consciousness, or verbal reasoning, rather it refers to the theoretical constructions and models used to explain aspects of behaviour that cannot be readily characterized in terms of simple S-R or reflex mechanisms. - Cognitive mechanisms: involve an internal representation or “mental” record of something, and rules for manipulating that mental record. o Internal representations may encode various types of information, such as particular features of stimuli or relations between stimuli. o They cannot however be investigated directly by looking into the brain. Animal Memory Paradigms: - Memory: is commonly used to refer to the ability to respond on the basis of information that was acquired earlier. o Memory is existent in animals as identified by the fact that their current behaviour is based on some aspect of their earlier experiences. - Evidence of learning is also identified on the bass of changes in behaviour due to earlier experiences. - Phases of Learning and Memory 1. Acquisition: exposure to a certain kind of stimuli or information. a. Learning: the study is primarily on the acquisition phase. i. They involve manipulations of the conditions of acquisition. b. Memory: study acquisition only to the extent that it is relevant to retention and retrieval. 2. Retention Interval: the information that was acquired is then retained for some time. a. Learning: retention interval is typically not varied and is always fairly long (short-term changes in behaviour are not considered to be learning) b. Memory: interval is often varied to determine how the availability of the acquired information changes with time. 3. Retrieval: reactivation of the information that is encountered during acquisition. a. Learning: conditions of retrieval are kept constant. b. Memory: testing on circumstances of retrieval. 2 i. Different conditions of retrieval. - Learning tests on acquisition whereas memory tests are more focused on retention interval and retrieval. - Memory Mechanisms have been classified in various ways depending on what is remembered, and how long the memory lasts, and the mechanisms involved in the memory. - Schachter and Tulving: Five types of Memory 1. Procedural Memory 2. Perceptual Memory 3. Semantic Memory 4. Primary or Working Memory 5. Episodic or Declarative Memory - Research on classical or instrumental conditions involve procedural memory o Procedural memory: reflects knowledge about relationships among features of the environment and mediates the learning of behaviour and cognitive skills that are performed automatically. - Studies of comparative cognition have examined episodic memory o Episodic memory: is memory for specific events. Working and Reference Memory - Study: Hunter; o Simple memory task o Phase one:  Placed rats into an apparatus consisting of a start area from which the animals could enter into one of three goal boxes  Only one goal box had food in it on each trial and the goal box with the food was marked by turning on the light above it at the start of the trial.  Animals learned to choose goal box with light. o Second phase:  Light on top of the goal box remained on for very short period of time, then turn off while animals were detained in start area for various lengths.  This forced the animals to remember which goal box was light up in order to find the food. o The longer the animals were delayed, the more likely they were to make a mistake. o Problem: once the trial was finished the information they learned in this procedure was no longer useful in the next trial because the food could be in any one of the goal boxes – this tests for working memory. - Working Memory: is operative when information has to be retained only long enough t complete a particular task, after which the information is best discarded because it is not needed or may interfere with successful completion of the next trial. o It is often short lasting o E.g. of working memory is the retention, for a limited duration, of recently acquired information. - Reference Memory: is long-term retention of information necessary for the successful use of incoming and recently acquired information. o Information about the relation between the light and the food had to be remember on all trials which was using reference memory. 3 - Delayed-matching-to-sample: which is a laboratory procedure that was developed with much regard for the behavioural pre-dispositions of animals and can be adapted to the study of how animals remember a variety of different events. - Species-specific-behavioural-specialization: test spatial memory, or memory for particular locations. Delayed Matching to Sample (DMTS) - refinement of Hunters original procedure. - Tests on participants with schizophrenia. o Phase One:  Participants are exposed to a cue that identifies the correct response on a particular trial.  Stimuli is removed before the participant can perform the behaviour.  Stimuli consisted of dark and light voxels and were presented for 500 milliseconds, followed by the choice alternatives.  Responding to the choice stimulus that was the same as the sample was the correct response.  The location of the alternative could not be used as a basis for making the correct choice.  The test stimuli appeared right after the sample and remained available until the subject made a choice. o Phase Two:  Once the subject learned to make the correct choice 80% of the time a four or eight-second delay was introduced.  The two groups preformed very well when matching did not include a delay however, participants showed a deficit in performance when trials included alternatives.  When there was a delay participants showed a deficit in performed indicting a problem with working memory. - This procedure was adapted to investigate how animals remember a variety of stimuli, including visual shapes, numbers of responses performed, presence or absence of reward etc. - Matching to sample is also useful to address questions that extend beyond memory mechanism into nonverbal ways of communication. Procedural Determinants of DMTS - Critical aspects to determining the accuracy f performance 1. Natural of the stimulus that serves as the sample 2. Duration of exposure to the sample at the start of the trial 3. Delay interval after the sample. Study: Grant - tested pigeons in a skinner box that had three pecking keys in a row on one wall above the food. - The keys were colours, which could be projected on the pecking keys. - At the start of each trial they center key was illuminated with a white light - The pigeon was required to peck the white light to make sure it was facing the response keys. 4 o After this the sample colour for that trial was presented on the center key for 1, 4, 8 or 14 seconds. o This was followed by a delay interval of 0, 20, 40, or 60 seconds after which the two side keys were illuminated, one with the sample matching colour the other was an alternative. o After the bird made its choice, all the keys would turn off for a 2-min intertribal interval. - Results: o If they pecked randomly they would have been correct 50% of the time. o Better-than-chance performance indicates the use of working memory o The accuracy of matching decreased as longer delays were introduced between exposure to the sample and opportunity to make the choice. o Performance improved if the birds were exposed to the sample for longer periods o Accuracy in the DMTS procedure decreased as a function of the delay interval and increased as a function of the duration of exposure to the sample stimulus. - Trace-decay hypothesis: o The oldest and simplest account of memory and memory loss o This hypothesis assumes that presentation of a stimulus produces changes in the nervous system that gradually dissipate, or decay, after the stimulus is turned off.  The longer, or more intense stimuli are presumed to produce stronger stimulus traces  Yet no matter what the initial strength of the trace, it is assumed to decay at the same rate after the stimulus ends. o The extent to which the memory of an event controls behaviour depends on the strength of the stimulus trace at that moment,  The stronger the trace, the stronger is the effect of the past stimulus on the organisms behaviour.  Increasing the delay interval in the matching-to-sample procedure reduces the accuracy of performance; b/c the trace of the sample stimulus is weaker after longer delays.  In contract, increasing the duration of exposure to the sample improves performance, b/c the longer stimulus exposures establish stronger stimulus traces. o It also assumes that forgetting functions reflect fairlu directly the strength of memory for the sample stimulus at different delay intervals. - Presenting the choice alternatives without a delay makes the task a bit easier and facilitates learning Study: Sargission and White: - same test just with different delay intervals from the nset to see if better memory could be trained by using longer delay intervals from the beginning of training - Phase one: o G1: delay between sample and choice stimuli was always 2 seconds o G2: delay was 4 seconds o G3: delay was 6 seconds. o Control Group: trained with usual procedure with no delay.  Each group had to get 80% of the tests correct - Phase Two: o All birds were tested with delays ranging from 0-10s 5 - Results: o Control group: showed the standard forgetting function, their rate of errors increase as the delays increased o There was no decline in pigeons that were trained with the 6s. o The other two groups were between o The results clearly show that forgetting function do not directly reflect the decay or fading of memory of the sample stimulus as a function of time, rather, test performance depends on the similarity between the conditions of testing and the conditions of training. Response Strategies in Matching to Sample - the matching to sample procedure is analogous to a discrimination problem in that the participant has to respond to the correct stimulus and refrain from responding to the incorrect one to get reinforced. - In discrimination learning participants appear to use the combined response strategy - In contrast participants in matching to sample spear to focus primarily on the correct choice. General vs Specific Rule Learning. - Same- as Rule: choose the choice stimulus which is the same as the sample - Another choice could be that animals learn a series of specific rules or stimulus response relations. - Most matching to sample procedures can be solved either by learning a general same-as rule, or by learning a series of specific stimulus-response relations. o Specific stimulus-response learning should not facilitate performance with new stimuli – b/c the acquired response has not been learned yet. o General rule learning predicts considerable positive carryover, b/c same as-rule can be used to solve any matching-to-sample problem, o In tests of transfer from one MTS problem to another, general earning should produce better performance than specific rule learning. - The greatest variation in possible samples occurs in what is called a: Trials-Unique Procedure: where a different stimulus serves as the sample on each trail and is paired with another stimulus during the choice phase. o b/c the sample stimulus is not presented on more than one trial, accurate performance with the trials-unique procedure is possible only if the participants learns to respond on the basis of a general same-as rule. Spatial Memory in Mazes - Morris Water Maze o First time subjects are place in water they swim until the find the platform and then allowed to remain there for 15-20 seconds. o Subsequent trials subjects have to find the platform based on spatial cues because the platform is not visible. o Results: the subjects received four trials per day. o Learning progressed fairly rapidly as they learned the task, the subjects took less time to find the platform and took a more direct route 6 o The largest improvements in performance occurred from the first to the second day. - Radial Arm Maze o b/c the morris water maze was not a natural occurring event o Radial maze take advantage of the natural process of finding food in an animals environment. o Therefore the animals have to remember where they last obtained food and void that location until the food there is replenished. o Study:  There were eight arms radiating from a central choice area and a food cup in each of the arms  Before starting each trial a pellet of food is placed in each food cup  One a food pellet has been consumed, that arm of the maze remains empty for the rest of the trial.  Animals need to then remember where they last ate o Results:  Entering an arm that had not been visited previously was considered to be a correct choice.  During the first five tests after familiarization with the maze, the rats made a mean of nearly seven correct choices during each test.  With continued pracitsed, the mean number of correct choices was always above seven, making seven the baseline. o The radial maze task takes advantage of foraging tactics that rats acquired through their evolutionary history. o There are several ways the rats could have chosen to enter only previously unselected arms 1. Mark each arm they visit with a drop of urine 2. They could select arms in a fixed sequence, a. yet they do not seem to used either of these tactics.  Rats appear to use distinctive features of the environment, such as window, doors etc. as landmarks and locate maze arms relative to those landmarks. - Spatial location is identified relative to distal room cues, not to local stimulus inside the maze. - By adding more arms to the end of the radial maze, investigators have explored the limits of working memory o Rats are able to remember 16-24 spatial locations in a food-depletion working memory task. - Study: Beatty and Shavalia: o Allowed rats to make
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