Simultaneous Discrimination Task Research Articles

Simultaneous and successive colour discrimination in the honeybee (Apis mellifera)

The colour discrimination of individual free-flying honeybees (Apis mellifera) was tested with simultaneous and successive viewing conditions for a variety of broadband reflectance stimuli. For simultaneous viewing bees used form vision to discriminate patterned target stimuli from homogeneous coloured distractor stimuli, and for successive discrimination bees were required to discriminate between homogeneously coloured stimuli. Bees were significantly better at a simultaneous discrimination task, and we suggest this is explained by the inefficiency with which the bees' brain can code and retrieve colour information from memory when viewing stimuli successively. Using simultaneous viewing conditions bees discriminated between the test stimuli at a level equivalent to 1 just-noticeable-difference for human colour vision. Discrimination of colours by bees with simultaneous viewing conditions exceeded previous estimates of what is possible considering models of photoreceptor noise measured in bees, which suggests spatial and/or temporal summation of colour signals for fine discrimination tasks. The results show that when behavioural experiments are used to collect data about the mechanisms facilitating colour discrimination in animals, it is important to consider the effects of the stimulus viewing conditions on results.

SIMULTANEOUS VISUAL DISCRIMINATION IN ASIAN ELEPHANTS

Two experiments explored the behavior of 20 Asian elephants (Elephas aximus) in simultaneous visual discrimination tasks. In Experiment 1, 7 Burmese logging elephants acquired a white+/black- discrimination, reaching criterion in a mean of 2.6 sessions and 117 discrete trials, whereas 4 elephants acquired a black+/white- discrimination in 5.3 sessions and 293 trials. One elephant failed to reach criterion in the white+/black- task in 9 sessions and 549 trials, and 2 elephants failed to reach criterion in the black+/white- task in 9 sessions and 452 trials. In Experiment 2, 3 elephants learned a large/small transposition problem, reaching criterion within a mean of 1.7 sessions and 58 trials. Four elephants failed to reach criterion in 4.8 sessions and 193 trials. Data from both the black/white and large/small discriminations showed a surprising age effect, suggesting that elephants beyond the age of 20 to 30 years either may be unable to acquire these visual discriminations or may require an inordinate number of trials to do so. Overall, our results cannot be readily reconciled with the widespread view that elephants possess exceptional intelligence.

THE TRANSFORMATION OF CONSEQUENTIAL FUNCTIONS IN ACCORDANCE WITH THE RELATIONAL FRAMES OF SAME AND OPPOSITE

Although the literature on reinforcement in behavioral psychology is extensive, few studies have examined the derived transformation of reinforcing functions in accordance with equivalence classes, and no published research has yet examined the derived transformation of consequential functions in accordance with nonequivalence relations. In the present study, which consisted of four experiments, the basic preparation was as follows. First, an arbitrary stimulus, B2, was established as a conditioned punisher, using direct stimulus pairing. Following nonarbitrary relational training, designed to establish SAME and OPPOSITE contextual cues, subjects were exposed to arbitrary relational training using these contextual cues to establish A1 as the same as B1 and C1, and as opposite to B2 and C2. Subsequently, C2 (based on its Same relation with B2) functioned as a punisher and C1 (based on its Opposite relation with B2) functioned as a reinforcer in a simultaneous discrimination task. Critically, the C1 stimulus acquired reinforcing functions, based on the derived relation of Opposite, although no such function had actually been established for any member of the network. Furthermore, these effects were observed across ABA reversals in the baseline contingencies.

Human implicit memory for irrelevant dimension values is similar to rats’ incidental memory in simultaneous discrimination tasks

Participants completed a category-learning task in which they needed to discover which of three stimulus dimensions (shape, color or size) was relevant. After meeting a learning criterion (nine of 10 consecutive correct responses), participants continued making categorization choices and response latencies associated with these trials were examined. In both Experiments 1 and 2, people responded reliably faster when correct responses matched the previous responses with respect to irrelevant dimension values. Thus, they demonstrated a form of incidental short-term memory analogous to that we previously reported in studies of rats. In Experiment 2, participants' explicit memory for irrelevant dimension values was assessed after category learning was complete. The results indicated that people were unaware of the irrelevant dimension values encountered on trials preceding surprise probe trials. This indicates that memory for the irrelevant dimension values was implicit (i.e. unconscious). The findings are discussed with respect to both human and non-human studies of hippocampus-independent memory and implicit memory.

Reverse lateralization of visual discriminative abilities in the European starling

Previous experiments on visual feature discrimination abilities have consistently shown a right-eye system lateralization in pigeons, Columba livia, and young domestic chickens, Gallus gallus domesticus, both nonpasserine species. Recently, however, it has been shown that photoreceptor distribution in the left and right retinas are asymmetrical in the European starling, Sturnus vulgaris, a passerine species. Single cone receptors are significantly more abundant in the left retina, which suggests that starlings should perform visual discrimination tasks more proficiently with the left eye, in contrast to previous findings with nonpasserines. We tested this hypothesis using the technique of monocular occlusion. In the first experiment, starlings were tested on a simultaneous visual discrimination task in three conditions: binocular (both eyes), left monocular (left eye only) and right monocular (right eye only). Subjects in the binocular and left-monocular conditions achieved significantly higher performance scores on the discrimination task than birds in the right-monocular condition. A second experiment found similar results, with birds in the left-monocular condition learning the discrimination task more than twice as quickly as those in the right-monocular condition. Subsequent tests with the alternative eye for both groups indicated no interocular transfer. These findings suggest that visual discriminative abilities in starlings are asymmetrical, and that they are lateralized in the opposite eye system than has been reported for all other species tested to date.

Simultaneous Pattern Discriminations by Pigeons Reveal Absence of Mirror-Image and Left-Right Confusions

In a simultaneous discrimination task, pigeons were first trained with two patterns: one rewarding (A+) and the other unrewarding (B-) that contained the same components (the symbols: c, d, ■ and <) but displayed in a different spatial layout. They were then tested for their choices of patterns: (1) A+ vs. its mirror image (MI); (2) A+ vs. its left-right reversal (LR); (3) MI vs. other layouts (OL) of the symbols; (4) LR vs. OL. In the first two conditions, A+ was chosen over its MI and LR reversal (i.e., no MI or LR confusions were found). In the last two conditions, MI and LR were not chosen over the OL, that is, they were not treated as substitutes for the A+. On the contrary, the OL stimuli were chosen over the transformations of A+. In all cases, the discriminations revealed a failure to confuse the A+ with its transformations, as predicted from work showing that the position of pattern components is important in pattern recognition.

Transfer and Stimulus Equivalence Classes Derived From Simultaneously Presented S+ and S- Stimuli

This study examined the effect of spatial contiguity on derived relational responding and transfer in populations with different mental ages: normal adults (Experiment 1), normal adolescents (Experiment 2), normal primary students (Experiment 3), adolescents with learning disabilities and a normal 7-year-old child (Experiments 4 and 5), and pre-school children (Experiment 6). The basic training and test sequence was the same in all experiments. After being trained on four simultaneous discrimination tasks with A and B stimuli (A1+/B1-, A2+/B2-, B1+/C1-, B2+/C2-) the subjects received match-to-sample probes measuring conditional relations between all directly and indirectly paired stimuli. Then, the subjects received transfer training (A1-clap, A2-wave), followed by transfer tests. Nineteen of the 21 subjects learned the training tasks. All these 19 subjects showed stimulus equivalence and transfer (A1-B1-C1-clap; A2-B2-C2-wave). These findings show that spatial contiguity, even among discriminative stimuli with incongruous functions, is a powerful procedure for establishing equivalence classes and transfer.

Glucocorticoid receptor impairment enhances impulsive responding in transgenic mice performing on a simultaneous visual discrimination task.

Transgenic mice with impaired glucocorticoid receptor (GR) function were tested for their ability to learn and perform a series of simultaneous visual discriminations which allowed a dissociation between accuracy of discrimination from those of motivation and behavioural disinhibition. Animals were first trained on an operant five-choice simultaneous discrimination autoshaping procedure, followed by a continuous reinforcement schedule on that task. Subsequently, the number of choices was limited to two and data were analysed according to the mathematical methods of signal detection theory (SDT). The effects of GR-antisense expression on accuracy when different rates of responding were required were studied under different fixed ratio response requirements (FR1-FR10). Autoshaping was retarded in transgenic animals and accuracy was impaired in both the five-choice and the two-choice discrimination tasks, although transgenic mice showed clear evidence for learning. Under conditions of low response requirements, transgenic mice showed increased response and cognitive biases, but reduced perceptual bias, and a behavioural disinhibition, characterized by a reduction in errors of omission, decreased response latencies and increased number of responses during the inter-trial interval. Increasing the response requirement improved performance in transgenic animals as reflected by enhanced accuracy. Moreover, transgenics were less susceptible to the deleterious effects of higher response requirements, as indicated by relatively unaffected bias measures in this group, while bias increased in controls. These results indicate that altered performance in GR-antisense transgenic animals cannot simply be interpreted as a mnemonic deficit, but that altered motivation and enhanced impulsive responding may account for some of these impairments.

Muscarinic cholinergic neuromodulation reduces proactive interference between stored odor memories during associative learning in rats.

Previous electrophysiological studies and computational modeling suggest the hypothesis that cholinergic neuromodulation may reduce olfactory associative interference during learning (M. E. Hasselmo, B. P. Anderson, & J. M. Bower, 1992; M. E. Hasselmo & J. M. Bower, 1993). These results provide behavioral evidence supporting this hypothesis. A simultaneous discrimination task required learning a baseline odor pair (A+B-) and then, under the influence of scopolamine, a novel odor pair (A-C+) with an overlapping component (A) versus a novel odor pair (D+E-) with no overlapping component. As predicted by the model, rats that received scopolamine (0.50 and 0.25 mg/kg) were more impaired at acquiring overlapping than nonoverlapping odor pairs relative to their performance under normal saline or methylscopolamine. These results support the prediction that the physiological effects of acetylcholine can reduce interference between stored odor memories during associative learning.

Visual lateralization of pattern discrimination in the bottlenose dolphin ( Tursiops truncatus)

The aim of the present study was to investigate whether bottlenose dolphins have cerebral asymmetries of visual processing. The monocular performance of the adult dolphin Goliath was tested using a large number of simultaneous multiple pattern discrimination tasks. The experiments revealed a clear right eye advantage in the acquisition and the retention of pattern discriminations as well as asymmetries in the interhemispheric transfer of visual information. As a result of a complete decussation at the optic nerve, this right eye superiority is probably related to a left hemisphere dominance in visual processing.

Der Feldermonitor – eine neue Möglichkeit der Lernforschung mit Tieren und Ergebnisse bei visuellen Differenzierungsaufgaben von Zwergziegen

Abstract. Title of the paper: A general purpose Computer system for behavioral conditioning experiments, named "Feldermonitor" – a new possibility for learning experiments with animals and results of visual discrimination tasks in dwarf goats The precise and automatised testing of sensoric as well as cognitive abilities of pets and livestock becomes increasingly important regarding both, the objecitve evaluation of their welfare and the develpoment of new automatic animal management facilities. The learning apparatus, named Feldermonitor and introduced here, proved to be a valuable apparatus for leaming experiments allowing continuous testing of leaming behaviour of animals under group as well as individual housing conditions. The developed hard and soft ware enables the tested animals to choose simultaneously among up to 12 options, which will confront them with a maximum of four elements of rewarding, informing or sanctioning. The experiments described were performed with dwarf goats. The animals were tested using simultaneous discrimination tasks with two or four Stimuli and being rewarded with small portions of water after each success. Comparing mean learning curves it can be shown, that in case of consecutive leaming tests, successful leaming Starts eariier as well as faster with each additionally performed test. The rapidity of leaming increases also, if different discrimination tasks are offered consecutively. The coefficient of variation for learning success among animals was 10 to 20%, indicating high individual differences.

Interocular transfer of learning in horses ( Equus caballus)

Summary Interocular transfer (IOT) of pattern discriminationswas studied in two horses (Equus caballus). An Anglo-Arabian mare and a Paint gelding were monocularly occluded and conditioned to choose the positive stimulus in a simultaneous two-choice discrimination task. When a criterion of ≥18/20 correct responses over two consecutive blocks of 20 trials was reached, the trained eye was covered and the stimuli presented to the untrained eye. Testing was continued until criterion was reached with this eye. Four sets of stimuli were presented in this manner. Additionally, two reversal discrimination problems were tested. Stimuli consisted of two-dimensional black patterns on a white background and were presented in a vertical configuration. The horses demonstrated high levels of interocular transfer on the four problems and on the reversal discriminations. The results provide evidence that, contrary to beliefs held by many people, horses are capable of interhemispheric transfer of visual information.

Discrimination of multidimensional geometrical figures by chickens: categorization and pattern-learning

Japanese bantam hens were trained to discriminate between geometrical figures varying along four integral dimensions. Only one dimension predicted food: selections of sharp-cornered figures were reinforced, while selections of rounded figures were not. In experiment 1, hens were subsequently trained to discriminate between nine figure pairs in a simultaneous discrimination task. Because single pairs contained multiple redundant cues, whereas the relevant dimension was obvious only across stimulus pairs, the results revealed effects of both generalization and reversal learning. Accordingly, learning speed was enhanced for later discriminations. Experiment 2 tested the hens’ transfer performance to unknown pairs, following experience of 9 or 18 figure pairs. Four of seven hens showed reliable transfer after experience with 9 figures, but only three showed transfer after experience with 18 figures, indicating lower transfer with higher number of stimulus pairs learned. In experiment 3, hens were trained to discriminate 27 figure pairs. Discrimination ratios further decreased and the groups of pairs differed significantly in their ratios of discrimination. Individual hens’ pecking behaviour was analysed in relation to each dimension of single figures and in relation to relative differences in the levels of dimensions between paired figures. Hens were shown to be oriented towards irrelevant information and more towards relational and configurational than elemental and dimensional aspects. The results are discussed in the biological context of individual recognition in chickens’ dominance hierarchies, in which we suppose that chickens identify individual flock mates by representation of their visual pattern rather than by single characteristics.

Learning from others' mistakes: a paradox revisited

Some researchers have reported the paradoxical finding of enhanced social learning when naive observers learn from unskilled rather than skilled demonstrators, particularly in discrimination tasks. In two experiments with starlings,Sturnus vulgaris, I considered whether this enhanced learning is because the observer (1) sees incorrect responses only, (2) sees both correct and incorrect responses or (3) sees an increase in the proportion of correct responses over trials. In experiment 1, individual starlings observed a demonstrator bird perform multiple simultaneous discrimination tasks. In one group, the demonstrator always picked the correct stimulus; in another group, the demonstrator always picked the incorrect stimulus; in a third group, the demonstrator consistently picked the correct stimulus 50% of the time. Those subjects that observed only incorrect choices performed significantly better than the other two groups, but none of the birds achieved the 90% correct performance criterion. Experiment 2 involved a single discrimination task; thus, a fourth group was added to control for individual learning. Again, subjects that observed only incorrect responses learned the discrimination significantly more quickly than the other three groups. Subjects that observed the demonstrator make both correct and incorrect responses were equally likely to select the same (correct) or opposite (incorrect) stimulus when the demonstrator picked the correct stimulus. When the demonstrator picked the incorrect stimulus, however, these subjects were significantly more likely to pick the opposite (correct) stimulus. These findings suggest that when learning a discrimination problem, observing a foraging companion's lack of success is more informative than observing its success.

Emergent simple discriminations and conditional relations in children, intellectually impaired adults, and normal adults.

Previous research has shown that when, under non-reinforced conditions, stimuli are added to S+ and S- stimuli in simultaneous discrimination tasks, transfer between paired stimuli is likely to occur. The present study examined whether this procedure also leads to the formation of conditional relations between paired stimuli. In Experiments 1, 2, and 3, normal pre-school children were trained on a simultaneous discrimination task with A1 reinforced and A2 not reinforced (A1+/A2-). Then they received two tests (no programmed consequences): one with B stimuli superimposed on the A stimuli (A1B1/ A2B2), and one with B stimuli only (B1/B2). Subjects who selected A1B1 and B1 also received conditional discrimination tests: one with B1 or B2 as samples and A1 and A2 as comparisons (B-A), and one in which the functions of these stimuli were reversed (A-B). Intellectually impaired adults and normal adults served in Experiments 4 and 5, respectively. These experiments were basically the same except that the subjects were also given the opportunity to demonstrate transfer from B to C via BC (B1C1/B2C2 and C1/C2 tests). Most children (75%) and intellectually impaired adults (75%) treated the conditional discrimination probe tasks as simple discriminations and typically selected the trained and derived S+ stimuli. The remaining children, intellectually impaired adults, and all normal adults related all directly and indirectly linked stimuli of the same functions conditionally to one another (A-B, B-C, A-C, and vice versa). The present findings suggest that, as humans develop, conditional stimulus relations may emerge from tasks and stimulus configurations that are increasingly remote from traditional conditional discrimination tasks.

Effects of selective antagonism or depletion of the cholinergic system on visual discrimination performance in rats

A two-lever simultaneous visual discrimination task was used to study the effects on performance in Long-Evans rats of the muscarinic antagonists scopolamine (0.0125, 0.05, 0.2 and 0.8mg/kg s.c.), the M(1) antagonist pirenzepine, the M(2) antagonist AF-DX 116, the M(3) antagonist UH-AH 37 (each 3.2, 10, 32µg/rat, i.c.v.), and the cholinergic depleting agent, hemicholinium-3 (0.04, 0.2, 1.0 and 5.0µg/rat i.c.v.). Scopolamine dose-dependently decreased accuracy, increased the number of trials on which the rats failed to respond, and significantly lengthened latency to respond. Only the highest doses of hemicholinium-3, pirenzepine and AF-DX 116 reduced accuracy and increased errors of omission as well as response latency. UH-AH 37 reduced overall task performance at 10 and 32µg, suggesting that antagonism of both M(3) and other muscarinic receptors (including M(1)) had a greater effect on performance than selective antagonism of the M(1) or M(2) receptors. These data indicate that the disruptive effects of cholinergic antagonism on attentionally demanding tasks are strengthened by activity at multiple subtypes of the receptor.

The effect of dizocilpine (MK-801) on spatial and visual discrimination tasks in the rat

The present experiments investigated the effect of the non-competitive N-methyl-d-aspartate (NMDA)-receptor antagonist, dizocilpine (MK-801) (0.075mg/kg) on acquisition and reversal of either a spatial or a visual, appetitively rewarded, simultaneous discrimination task in a Y-maze. The experimental design for the spatial and the visual discriminations was identical, the only difference between the tasks being the nature of the stimulus. Dizocilpine had not effect on acquisition of the spatial task although, when this task was reversed, dizocilpine-treated rats took significantly more trials to reach criterion. On the visual task, dizocilpine impaired both acquisition and reversal. Thus, systemic administration of dizocilpine did not produce a specific spatial learning impairment. The fact that dizocilpine impaired reversal but not acquisition in the spatial task argues against a global performance deficit. Although both the acquisition and reversal phases of the experiment make equal sensory and motor demands on the animal, reversal involves specific learning processes that may be disrupted by dizocilpine.

Effects of imipramine and mirtazapine on operant performance in rats

AbstractThe effects of the tricyclic antidepressant imipramine and the atypical antidepressant mirtazapine were compared on the performance of rats in three operant procedures: a differential reinforcement of low rates schedule (DRL), a delayed matching to position (DMTP), and simultaneous visual discrimination tasks. Both compounds improved performance in the DRL task in a similar dose‐related manner. Imipramine, but not mirtazapine, disrupted performance in the visual discrimination task. Imipramine reduced accuracy and increased response latencies and missed trials. Neither compound effected accuracy in the DMTP; both compounds caused some slowness of responding and imipramine caused several animals to fail to respond in a manner similar to that observed in the visual discrimination task. These data suggest that although imipramine and mirtazapine are similarly effective in putative tests of antidepressant activity, imipramine has a greater tendency to disrupt other aspects of cognitive performance, as well as exert generally depressive effects on operant responding.

The Effects of Subject-Controlled Pacing and Task Type on Sustained Attention and Subjective Workload

Abstract The present study explored the effects of subject-controlled pacing in vigilance. One group of subjects (production) were given the opportunity to control the event rate (ER) during the course of a vigil. A second yoke-control (reception) group monitored the same presentation of events determined by those in the production condition, but were not permitted to alter the display. A third group (control) monitored a schedule of events that varied at random. Half the subjects in all conditions were assigned to a simultaneous discrimination task; the other half were assigned to a successive discrimination task. All the subjects rated the workload associated with the task. The performance of subjects in the production condition was superior to that of subjects in the reception condition, which in turn, was superior to that of subjects in the control condition. No main effects for task type or workload were observed. The results support the idea that allowing monitors to set their own pace of observing ...

Amodal completion in mouse vision.

The question of whether phenomena of human perception such as amodal completion are also present in visual perception in the mouse was investigated. Three experiments based on a simultaneous-discrimination task were carried out with the aid of a jumping-stand similar to the one used by Lashley. The subjects were 36 male mice (DBA/J); 12 took part in each experiment. After reaching the learning criterion (87% correct responses), the mice performed 15 test trials which were interpolated between the learning trials. The test trials were constructed so as to allow the observation of any perceptual phenomena similar to amodal perception. Of the 36 subjects, 23 reached the criterion necessary to access the test phase. A significant number of them (17 out of 23, chi 2 = 5.261, p = 0.021) adopted a decisional strategy that seemed to indicate the occurrence of phenomena similar to amodal completion, and a trend in the same direction was observed in the performance of the other 6 subjects. The results allow the conclusion that a perceptual phenomenon which is similar to amodal completion in humans is present even at this phylogenetic level. Alternative interpretations are discussed.