Mere exposure to telereceptive cues facilitates intake of a novel flavor in chickens (Gallus domesticus)

This experiment investigated whether mere exposure to visual cues of a distinctively colored solution (water) would facilitate intake of a novel flavor (vinegar) of the same distinctive color. Eighty-four chicks received access to clear water, clear vinegar, red water, or red vinegar under conditions which permitted drinking or they received access to clear water or red water under conditions (mere exposure) which prevented drinking. All chicks were then tested on intake of red vinegar. Chicks which had received mere exposure or ingestional experience with red-colored water drank reliably more red vinegar than did chicks which had received prior ingestional experience with the novel taste, vinegar, but not with the visual cues of red. However, intake of red vinegar was reliably greater following ingestional experience with red water than following visual exposure without ingestion. Results supported the mere exposure hypothesis.     

The use of spatial and local cues for orientation in domestic chicks (Gallus gallus)

Animal Cognition - Birds have been widely used to study spatial orientation. However, since different birds rely on different types of visual information to find goal locations (such as spatial...     

Geometric modules in animals' spatial representations: a test with chicks (Gallus gallus domesticus)

Recent work has shown that in place-finding tasks rats rely on the geometric relations between the goal object and the shape of the environment. We tested young chickens (Gallus gallus domesticus) on similar tasks in a reference memory paradigm to determine whether differences exist between species in the ability to use geometric and nongeometric spatial information. The main findings were that chicks: (a) encoded and used both geometric and nongeometric (featural) information; (b) did not use the overall spatial arrangement of the features; (c) relied primarily on nongeometric cues when faced with contradictory information. Two mechanisms are evident in chicks' spatial representations: a metric frame for encoding the spatial arrangement of surfaces as surfaces and a cue-guidance system for encoding conspicuous landmarks near the target. The possibility of hierarchical organization and species differences in these two mechanisms are discussed.     

Leap orders in male chickens (Gallus gallus domesticus): longitudinal evidence

Leap orders in pairs of male chickens were traced in a longitudinal study from near hatching to about 11 weeks of age. Birds were given a series of 39 day-long social separations, each followed by a day-long reunion. Tests for aggression occurred during the first 5 min of reunion. Pecks were frequent early in the test series, but soon diminished; leaps supplanted pecks as the most frequent response at about midseries, and abated in turn. To account for this dual pattern of the waxing and waning of aggressive responses, it was hypothesized that leap orders had formed in midseries, thus obviating further agonistic behavior. Support for the hypothesis was found: Early peck orders did not predict later leap orders, but early leap orders did predict subsequent leap and peck orders.     

Perception of the Ebbinghaus illusion in four-day-old domestic chicks (Gallus gallus)

In the Ebbinghaus size illusion, a central circle surrounded by small circles (inducers) appears bigger than an identical one surrounded by large inducers. Previous studies have failed to demonstrate sensitivity to this illusion in pigeons and baboons, leading to the conclusion that avian species (possibly also nonhuman primates) might lack the neural substrate necessary to perceive the Ebbinghaus illusion in a human-like fashion. Such a substrate may have been only recently evolved in the primate lineage. Here, we show that this illusion is perceived by 4-day-old domestic chicks. During rearing, chicks learnt, according to an observational-learning paradigm, to find food in proximity either of a big or of a small circle. Subjects were then tested with Ebbinghaus stimuli: two identical circles, one surrounded by larger and the other by smaller inducers. The percentage of approaches to the perceptually bigger target in animals reinforced on the bigger circle (and vice versa for the other group) was computed. Over four experiments, we demonstrated that chicks are reliably affected by the illusory display. Subjects reinforced on the small target choose the configuration with big inducers, in which the central target appears perceptually smaller; the opposite is true for subjects reinforced on the big target. This result has important implications for the evolutionary history of the neural substrate involved in the perception of the Ebbinghaus illusion.     

Preference for symmetry is experience dependent in newborn chicks (Gallus gallus)

Spontaneous pecking preferences toward symmetric or asymmetric stimuli were tested in newborn chicks (Gallus gallus). A preference for asymmetric patterns was found in na?ve chicks (either 24 or 48 hours old), although a preference for symmetry appeared at retest after chicks had experienced standard rearing conditions (Experiments 1 and 2). Only food-experienced chicks preferred symmetric patterns; food-deprived and hand-fed chicks did not show any preference (Experiment 3). A key factor that allowed for the emergence of a preference for symmetry may relate to the improving of pecking sensorimotor skills occurring during active food manipulation. Possible explanations are discussed for the late emergence of the preference for symmetry and for the preference for asymmetry found in na?ve chicks.     

Social motivation and the use of distal,but not local,featural cues are related to ranging behavior in free-range chickens (Gallus gallus domesticus)

Animal Cognition - Animals can navigate an environment relying on different sources of information, such as geometrical or featural cues. The favoring of one type of information over another...     

Rudimental numerical competence in 5-day-old domestic chicks (Gallus gallus): identification of ordinal position

Numerical competencies were investigated for the 1st time in very young nonhuman animals. Chicks (Gallus gallus) learned to identify the 3rd, 4th, or 6th positions in a series of 10 identical positions (Experiment 1). Use of spatial information (i.e., distances) was ruled out in Experiment 2 (chicks generalized the reinforced response to an array of stimuli rotated by 90 degrees as compared with training) and Experiment 3 (chicks generalized their response to a series in which distances between the single positions had been manipulated). Chicks found the correct position even when both identity and distance of each position changed from trial to trial (Experiment 4). Overall, young chicks seemed to use ordinality when required to identify a target by its numerical serial position.     

Affiliation and aggression as related to gender in domestic chicks (Gallus gallus).

Social discrimination in male and female domestic chicks (Gallus gallus) was investigated by using (a) latencies of approach response, (b) simultaneous free choice, and (c) intersubject aggressive-pecking tests. In approach-response tests, females showed shorter latencies when tested with cagemates than when tested with strangers, whereas males showed shorter latencies when tested with strangers than when tested with cagemates. In simultaneous-choice tests, females spent more time near a cagemate, whereas males spent more time near a strange chick. In aggressive-pecking tests, both sexes pecked more at strangers than at cagemates; aggressive pecking at strangers, however, was higher in males than in females. It is argued that gender effects in social discrimination can be accounted for in terms of stronger social attachment in females and aggressive responses in males.     

Naturalistic psychophysics: thresholds of ducklings (Anas platyrynchos) and chicks (Gallus gallus) to tones that resemble mallard calls

Neonatal ducklings and chickens were tested for responsiveness to a pulsing pure tone that was as similar as possible to the mallard maternal alarm call. It is known that ducklings momentarily cease vocalizing when they hear the alarm call and that chicks do the same when they hear pure tones. The duration of peep suppression can thus be used as a measure of whether subjects of either species heard the stimulus. Chicks might not be as sensitive as ducklings to a mallard alarm call because the signal is less significant to them. An adaptive or staircase procedure was used to estimate absolute thresholds, and group psychometric functions were reconstructed for each species from the trial-by-trial data. Ducklings had lower thresholds than chickens as well as steeper psychometric functions to this stimulus. The results suggest that more sensitive and consistent behavioral responses can be elicited by naturalistic sounds than by more arbitrary acoustic stimuli.     

Flavour neophobia in gerbils (Meriones unguiculatus) and hamsters (Mesocricetus auratus)

Flavour neophobia in gerbils and hamsters was studied by comparing the ingestive/pouching behaviour of these animals when presented with either a familiar unflavoured peanut or a novel one that imparted basic flavours such as sweet, salty, sour, or bitter. Neophobia was expressed by an aversion towards the novel nut manifested by greater latency either to ingest it (gerbils) or to deposit it in the cheek pouch (hamsters) relative to that of the unflavoured one. This method, involving reactions to the taste of novel solid food, provides a more sensitive measure than the traditional one measuring intake of a novel flavoured fluid. The results indicated that gerbils and hamsters encountering either a sweet, salty, or sour nut for the first time showed a neophobic reaction. However, there was no apparent sign of neophobia when the animals were tested with a nut flavoured with quinine. The theoretical implications of these findings are discussed.     

The addition of saccharin to taste cues affects taste preference conditioning in thirsty rats

Previous failures to condition preferences for the unacceptable taste cues sucrose octaacetate (SOA) and citric acid (CA) using a reverse-order, differential conditioning procedure (Forestell & LoLordo, 2000) may have been the result of low consumption of the taste cues in training or of their relatively low acceptability to rats that are thirsty and hungry. In the present study, rats that were thirsty but not hungry readily consumed the SOA and CA conditioned stimulus solutions in training. In test, stronger preferences were displayed for CS+ if the taste cues had been mixed in water (i.e., for the previously unacceptable taste cues) than if they had been made more acceptable by the addition of saccharin in training and test. In Experiment 2, again with rats that were thirsty but not hungry, stronger preferences for CS+ were observed when taste cues were presented in water in the test than when they were presented in saccharin. Addition of saccharin to the taste cues in test eliminated the preference for CS+.     

Reinforcer quality matters: A test of the Mathematical Principles of Reinforcement with domestic hens (Gallus gallus domesticus)

This study evaluated the ability of Killeen's (1994) Mathematical Principles of Reinforcement to account for the effects of changes in reinforcer quality on hens' rates of responding on fixed‐ratio schedules. Hens were trained to peck a key on a fixed‐ratio schedule of reinforcement and then experienced an ascending series of ratio values in two separate conditions. In different conditions, the food reinforcer was either wheat or puffed wheat. Response rates initially increased with increases in ratio requirement before eventually decreasing at larger ratios. Quantitative fits of the model accounted for the data well. The fits revealed that different foods were systematically associated with changes in the specific activation parameter, a, and these were consistent with previous reports of preference for those food items.