Martina Siemann

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The nucleus accumbens septi (Acc) is thought to be involved in the control of cognitive processes and to be implicated in the pathophysiology of schizophrenia. Because perceptual-cognitive distortions are a core symptom in schizophrenia, any evidence that the Acc intervenes in a sensory recognition task in an animal species would be of interest. Pigeons(More)
In order to survive and reproduce, individual animals need to navigate through a multidimensional utility landscape in a near-optimal way. There is little doubt that the behaviourally more advanced species can bring cognitive competencies to bear on this difficult task. Among the cognitive abilities that are helpful in this context is transitive inference.(More)
The derivation of the conclusion "Anna is bigger than Mary" from the premises "Anna is bigger than Paul" and "Mary is smaller than Paul" is considered an instance of transitive deduction. For a non-verbal presentation, the premise statements were here transformed into a multiple operant discrimination task. Adult subjects were trained with overlapping pairs(More)
Pigeons were trained to peck a certain number of times on a key that displayed one of several possible numerical symbols. The particular symbol displayed indicated the number of times that the key had to be pecked. The pigeons signalled the completion of the requirement by operating a separate key. They received a food reward for correct response sequences(More)
Four pigeons were given simultaneous discrimination training with visual patterns arbitrarily divided into two sets, with the stimuli in one set designated A1, B1, C1, and D1 and those in the other set designated A2, B2, C2, and D2. In sequentially introduced training phases, the pigeons were exposed to a series of reversals to establish AB and then CD(More)
Transitive inference is a kind of deductive reasoning. Given the premises "Anna is taller than Paul" and "Paul is taller than Mary", adults and older children easily conclude that "Anna is taller than Mary". However, a related transitive responding ability has also been demonstrated in younger children and some animals with non-verbal tasks. For this, the(More)
It is well known that when humans have to decide whether two differently oriented shapes are identical or mirror images their performance deteriorates as a function of the orientation disparity (mental-rotation effect). Here it is shown that the effect can also be obtained reliably with non-mirror-image, arbitrarily different polygons provided they are(More)
After responding to each element in varying, successive numerosity displays, pigeons (Columba livia) had to choose, out of an array of symbols, the symbol designated to correspond to the preceding number of elements. After extensive training, 5 pigeons responded with significant accuracy to the numerosities 1 to 4, and 2 pigeons to the numerosities 1 to 5.(More)
Fersen et al. (1991) (J. Exp. Psychol.: Anim. Behav. Process., 17: 334-341) trained pigeons to discriminate four overlapping pairs of stimuli A + B -, B + C -, C + D - and D + E - (+ rewarded, - penalized). When subsequently tested with a pair BD the pigeons showed a strong preference for stimulus B. A special value transfer theory was offered as an(More)