The discrimination of dog odours by humans

The domestic dog is able to identify both individual conspecifics, i.e. other dogs, and individual interspecifics, e.g. humans, by smell. Whilst humans can recognise individual members of their own species using olfactory information, it is unknown whether they can identify members of any other species in this manner. We examined the ability of humans to identify individual dogs by smell. Twenty-six dog owners were required to smell two blankets, one impregnated with the odour of their own dog, the other impregnated with the odour of an unfamiliar dog. Participants were required to indicate which of the odours smelt the strongest, which smelt the most pleasant, and which of the odours belonged to their own dog. Most of the participants (88.5%) were able to recognise the odour of their own dog. They showed no significant bias, however, in responding which of the odours they thought smelt the strongest or most pleasant. The results indicate that dogs produce odours that are individually distinctive to their owners, and highlight the fact that humans can recognise members of another species using olfactory cues--an ability presumably acquired without conscious effort.     

Visual discrimination of shape by humans

Reaction times to tachistoscopic exposure and a card-sorting task are the two methods by which visual discrimination of shape is studied. The results of experiments using both methods tally, i.e. the order of difficulty of the following shapes was: (1) (easiest) circle vs. triangle; (2) circle vs. square; (3) square vs. triangle; (4) (most difficult) triangle vs. diamond. These results are compared with those obtained by Sutherland, using octopus, and it is concluded that it should be possible to establish to what extent the system of visual analysis in humans differs from that postulated for both octopus and rat.     

Stimulus-outcome interactions during instrumental discrimination learning by rats and humans

The associative structure mediating goal-directed action was investigated using congruent and incongruent conditional discriminations. The stimulus was the same as the outcome in each component of the congruent discriminations, whereas the stimulus of one component of the incongruent discriminations was the same as the outcome of the other component. Humans, but not rats, learned the congruent discrimination more rapidly than the incongruent discrimination, a difference that the authors attribute to the fact that outcome-response associations caused response conflict in the incongruent discrimination. Moreover, responding was resistant to outcome devaluation following incongruent, but not congruent, training, suggesting that both humans and rats adopted a stimulus-response strategy to resolve the incongruent discrimination.     

Behavioral discrimination of click intensity in cat

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.     

Diurnal pattern of luminance discrimination in humans

The visual discrimination threshold can be considered as an image of the resolution power of the visual system. Measured with a psychophysical method, it shows a diurnal pattern with a low threshold in the morning, i.e., high sensitivity and an increase in the afternoon that persists until the early evening.     

Quantity discrimination by kittens of the domestic cat (Felis silvestris catus)

Animal Cognition - Quantitative abilities are well described in many species and in diverse life situations, including in the adult domestic cat. However, such abilities have been much less studied...     

The presence of a temporal discrimination in the conditioned emotional response with humans,

Six college students participated in matching-to-sample tasks. Conditioned emotional response (CER) training consisted of pairing a tone with a "painful" level of shock. Three of the subjects demonstrated response suppression, one subject showed facilitation, and two showed no change. Analysis of response rate during the tone interval indicated that, for those subjects who showed response suppression, the decrease in response rate was greatest immediately before onset of the unconditioned stimulus. This temporal discrimination was similar to that obtained with infrahumans.     

A comparison of event-related potentials of humans and rats elicited by a serial feature-positive discrimination task

The purpose of this experiment was to compare components of the human and rat auditory event-related potential (ERP) in a serial feature-positive discrimination task. Subjects learned to respond to an auditory target stimulus when it followed a visual feature (X → A+), but to not respond when it was presented alone (A−). Upon solving the task, the N2 component, which has been suggested to reflect the activation of inhibitory processes, was temporarily more negative in response to the target on A− than on X → A+ trials in both species. However, whereas a P3 component was present in the human participants, this component was absent in the rats. In both species, the amplitude of several ERP components, including the N2, decreased in the course of training. These results are discussed in the framework of contemporary models of associative learning.     

Multimodal discrimination learning in humans: Evidence for configural theory

Human contingency learning was used to compare the predictions of configural and elemental theories. In three experiments, participants were required to learn which indicators were associated with an increase in core temperature of a fictitious nuclear plant. Experiments 1 and 2 investigated the rate at which a triple-element stimulus (ABC) could be discriminated from either single-element stimuli (A, B, and C) or double-element stimuli (AB, BC, and AC). Experiment 1 used visual stimuli, whilst Experiment 2 used visual, auditory, and tactile stimuli. In both experiments the participants took longer to discriminate the triple-element stimulus from the more similar double-element stimuli than from the less similar single-element stimuli. Experiment 3 tested for summation with stimuli from either a single or multiple modalities, and summation was found only in the latter case. Thus, the pattern of results seen in Experiments 1 and 2 was not dependent on whether the stimuli were single modal or multimodal, nor was it dependent on whether the stimuli could elicit summation. This pattern of results is consistent with predictions derived from Pearce's (1987, 1994) configural theory.     

Multimodal discrimination learning in humans: evidence for configural theory

Human contingency learning was used to compare the predictions of configural and elemental theories. In three experiments, participants were required to learn which indicators were associated with an increase in core temperature of a fictitious nuclear plant. Experiments 1 and 2 investigated the rate at which a triple-element stimulus (ABC) could be discriminated from either single-element stimuli (A, B, and C) or double-element stimuli (AB, BC, and AC). Experiment 1 used visual stimuli, whilst Experiment 2 used visual, auditory, and tactile stimuli. In both experiments the participants took longer to discriminate the triple-element stimulus from the more similar double-element stimuli than from the less similar single-element stimuli. Experiment 3 tested for summation with stimuli from either a single or multiple modalities, and summation was found only in the latter case. Thus, the pattern of results seen in Experiments 1 and 2 was not dependent on whether the stimuli were single modal or multimodal, nor was it dependent on whether the stimuli could elicit summation. This pattern of results is consistent with predictions derived from Pearce's (1987, 1994) configural theory.     

A multidimensional scaling analysis of vowel discrimination in humans and monkeys

Multidimensional scaling (MDS) was used to compare perceptual maps for 10 synthetic English vowels in humans and Old World monkeys (Macaca fuscata andCercopithecus albogularis). Subjects discriminated among the vowels using a repeating background procedure, and reaction times were submitted to an MDS analysis to derive measures of perceived similarity. The dimensions that emerged related to the frequencies of the first(F1), second(F2), and third(F3) formants. Human data indicated a good match to previous MDS studies using rating procedures or confusion matrices: The dominant dimension mapped onto vowelF2, the phonetically most important formant, and the second and third dimensions mapped ontoF1 andF3, respectively.For monkeys, equal weightings occurred forF1 andF2, andF3 was not clearly represented. Monkey sensitivity to the formants appeared to relate to formant amplitudes. If monkeys are giving an accurate representation of the psychoacoustic relations among the formants, then our human results suggest that species-specific mechanisms, reflecting the salience of the phonetic feature of advancement, may contribute to vowel coding in humans.     

More or less: spontaneous quantity discrimination in the domestic cat

We examined spontaneous quantity discrimination in untrained domestic cats in three food choice experiments. In Experiment 1, we presented the cats with two different quantities of food in eight numerical combinations. Overall, the subjects chose the larger quantity more often than the smaller one, and significantly so when the ratio between the quantities was less than 0.5. In Experiment 2, we presented the cats with two pieces of food in four different size combinations. Again, subjects chose the larger piece above chance, although not in the combination where the largest item was presented. In Experiment 3, a subset of the cats was presented multiple times with two different quantities of food, which were hidden from view. In this case, the cats did not choose the larger quantity more often than the smaller one, suggesting that in the present experiments they mainly used visual cues when comparing quantities. We conclude that domestic cats are capable of spontaneously discriminating quantities when faced with different numbers or sizes of food items, and we suggest why they may not always be motivated to choose the larger quantity. In doing so, we highlight the advantages of testing spontaneous choice behavior, which is more likely to reflect animals’ everyday manner of responding than is the case when training them in order to test their absolute limits of performance which may not always coincide with their daily needs.