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Resourcd File

  1. 1. ANIMAL RESEARCH ON COGNITIVE MAPSThe initial discovery that mental representations of the spatial world were stored and could be usedto help find a particular place came from animal research.Tolman (1948) studied the way that rats learned in experimental mazes. Using conditioningtechniques, rats learned to follow a particular path to reach food. This learned path was thenblocked and it was found that instead of taking an alternative, previously reinforced path, the ratswould take a novel one which led more directly to the end goal. This suggested that some kind oflearning had occurred linking the whole maze, as they were aware of where the end was in relationto the start. Tolman termed this representation that they had acquired a cognitive map.Tolman, E.C. and Honzik, C.H. (1930a) Insight in rats. University of CaliforniaAim: To demonstrate that rats could make navigational decisions based on knowledge of the envi-ronment, rather than their directional choices simply being dictated by the effects of rewards.Method: A maze was used as illustrated below. Initially, rats had access to the whole maze: laterit was obstructed at point A, then at point B. The alternative route selected by each rat on eachtrial was recorded.Results: Initially, rats learned their way from the start to the Food box without obstructions andreliably used route 1, the shortest. When their path was blocked at A, the rats selected route 2 toavoid the obstruction and reached the Food on 92% of the trials. When the path was obstructed atB, 93% of the rats chose route 3 on the first test trial.Conclusion: Although the results of obstructing the maze at A could be interpreted as a simpleresponse to reinforcement - the rat chose the route that would most quickly lead to the Food, asit was the shortest available - the same cannot be said of the results of obstructing the maze atB. Here, the rats did not select the next shortest route (2), which would also have been blocked,but used their cognitive maps to deduce that the only available route was 3.Tolman and Honzik (1930b) and, more recently, Holtzman et al. (1999), have demonstratedthat animals that have had the opportunity to explore a maze are faster than those that have not.Regolin and Rose (1999) have shown that animals such as chicks can learn to take a detour.
  2. 2. Maier and Schneirla, (1935) also found that rats can also use cognitive maps to shorten theirjourney.As an alternative to laboratory experiments using mazes, animals can be tested using field studies. ToMenzel (1971) investigated the use of cognitive maps in a naturalistic environment and studiedchimps living in a large outdoor enclosure. The chimps were held indoors and, one by one, they weretaken to see food being hidden in 18 locations outside. When each chimp was released in the centre ofthe area to find the hidden food it took a route that minimised the distance it had to travel; it did notretrace the complex path that it had previously followed. The chimps choices enabled them to findmost of the food in the minimum time by exploiting their knowledge of the area. Therefore, they musthave been using cognitive maps, as they did not employ the previously encountered route.Furthermore, it would appear that the chimps cognitive maps were more than just records ofrelationships between places. In a second part of the experiment, Menzel (1971) took the chimps to18 new locations, half of which contained fruit (which chimps prefer) and the other half vegetables.Upon release, the chimps went to the locations where fruit had been hidden before those locationscontaining vegetables. Therefore, it seems that the cognitive maps provide information about theplaces as well as their geographical locations.Jacobs and Linman (1991) investigated the role of the cognitive map in allowing animals to search forfood that they had stored themselves. Each grey squirrel (Sciurus carolinensis) was released into a45m² area to bury 10 hazelnuts. The location of each food item was recorded and the nuts were thenremoved. The squirrels were returned to the area individually 2, 4 or 12 days later. New hazelnuts hadbeen placed in the individuals own hiding places and at an equal number of randomly chosen sites thathad been used by other squirrels (see the accompanying figures). The squirrels were more likely tofind nuts in places where they had buried them, even when they had to pass the sites chosen by othersquirrels.
  3. 3. Although the squirrels could clearly locate buried nuts by smell alone, they were preferentiallyseeking the ones that they had hidden on the basis of recalling each location, which suggests thatthey were using cognitive maps.Whishaw and Tomie (1997) showed that lesions to the fimbria-fornix (a region of the hippocampus)affected rats navigational abilities. The rats were trained to collect food pellets from one locationand take them to their home base. The locations of the release point and home base were thenmoved. If the new home base location was visible, the lesioned rats were able to take the food homeaccurately. If, however, the new location was hidden from view, these rats continued to return to theold home base location unlike the control rats that learned the reversal of locations after one trial.The rats with hippocampal lesions seemed unable to update their cognitive maps when the spatialrelationships changed in the environment.The importance of the hippocampus in navigation is also supported by evidence from natural variationsin hippocampal volume. Animals that have a large territory (Gaulin and Fitzgerald, 1989) and peoplewho navigate daily (Maguire et al., 2000) have a larger hippocampus.Look up and insert the findings of Capaldi, 2000; (bees):MagnetoreceptionEvidence from animals suggests that one important source of information about way-finding is the useof an internal compass that detects the Earths magnetic field, a process called magnetoreception.This is supported by physiological, anatomical and behavioural studies.Beason (1989) has found a compound called magnetite in the brains of a species of migrating bird (thebobolink, Dolichonyx oryzivorus). It is an iron-containing substance that is magnetic and is located inthe ethmoidal region (behind the nose). When Beason placed microelectrodes in the brain of anaes-thetised birds and altered the magnetic field around them, the neurones in this region responded.Although it is as yet unclear how these neurones might use this information, magnetoreception doesappear to make a significant contribution to the navigational skills of many birds, such as pigeons(Larkin and Keeton, 1976; Walcott and Brown, 1989), bobolinks (Beason, 1989) and robins (Wiltschkoand Wiltschko, 1988). Remarkably, evidence suggests that humans may have a similar facility to usemagnetoreception.In an investigation to assess the use of an innate magnetic sense by humans, Murphy (1989) testedthe ability of schoolchildren aged between 4 and 18 to judge direction. In a quiet room in theirschool, each child was shown four objects used in place of compass directions (such as a desk or apicture, in order to make the task sufficiently easy and memorable for young children). Using aspinning chair, the children were rotated clockwise and then anticlockwise, before stopping at eachcompass point in a random order. Each child made one estimate for each compass direction.
  4. 4. A comparison of males and females showed that the girls aged from nine upwards performedsignificantly better than chance. Boys were less accurate, achieving better than chance only in the 13-14 age group. To establish whether this ability was dependent on detecting the Earths magnetic field,Murphy tested 11-18-year-old girls in two conditions, with either a brass bar or a magnet attached tothe side of the head. She found that the girls could reliably pinpoint compass directions in the brassbar condition, but lost this ability in the magnet condition. The magnets would have disrupted theirinterpretation of natural magnetic fields, thus limiting their ability to use this cue to position. Thefindings suggest that humans can indeed use magnetic information to judge orientation. This abilityseems to be more effective in females, perhaps because males are taught to use other techniques andthus do not rely so heavily on this navigational strategy.Questions on Cognitive Maps in AnimalsOn a separate piece of paper, answer the following questions.1. Summarise (in your own words) the main finding of Tolman’s research.2. Which of the other research listed below Tolman’s, do you consider is the most supportive ofTolman’s original findings and why.3. Using Menzel’s research, explain the advantages of using a field study.4. Describe a comparative study that has adopted a physiological approach?5. Which study do you think is the most generalisable and which is the least generalisable andwhy.6. Design an experiment in how you might investigate/study whether humans havemagnetoreception.7. Plan an answer to the following question:‘Evaluate the use of animals in research on cognitive maps’.