Social interaction with siblings is necessary for visual imprinting of species-specific maternal preferences in ducklings (Anas platyrhynchos)

This study was conducted to examine the influence of various social rearing experiences on the development of imprinted visual maternal preferences in domestic mallard ducklings (Anas platyrhynchos) during the first 3 days of postnatal life. Twenty-four-hour-old ducklings were allowed to follow a stuffed mallard hen for 30 min. This experience resulted in a visual preference for the familiar mallard hen over an unfamiliar stuffed redhead (Aythya americana) hen in simultaneous choice tests at 48 hr and 72 hr only if the ducklings were reared in conditions allowing unrestricted social interaction with siblings, as would normally occur in nature. No visual preference for the familiar mallard model was found at 48 hr or at 72 hr if ducklings were reared in social isolation but allowed to see another duckling, reared with one duckling, or reared in a group of ducklings but denied the opportunity for direct social interaction. These results demonstrate the importance of normal social experience in the development of the visual imprinting of filial behavior in ducklings. Imprinting studies have traditionally employed isolation rearing and ignored the precocial bird's natural social context. Thus, the present findings raise doubts about the appropriateness of the usual methods of studying imprinting in the laboratory for an understanding of the process of filial imprinting in nature.     

A framework for the study of filial imprinting and the development of attachment

Filial imprinting is the process through which early attachment behavior becomes restricted to the mother and siblings. In the present paper it will be shown that the processes underlying imprinting in chicks (Gallus gallus) can be fruitfully analyzed by referring to the same mechanisms as are generally assumed to play a role in perceptual and associative learning. This can be achieved within a framework formulated to study the development of behavior in general. This offers the opportunity to apply the same general framework to the study of filial imprinting and the further development of attachment. The involvement of perceptual and associative processes in imprinting is discussed in some detail, while the broader implications of the present approach are indicated only briefly.     

Reinforcement by an imprinting stimulus versus water on simple schedules in ducklings

Ducklings (5 to 28 days old) were trained to peck a pole on fixed-ratio, fixed-interval, and multiple schedules using brief presentation of an imprinting stimulus as the response-contingent event. Other ducklings of the same age were trained similarly except that reinforcement consisted of access to water. With water reinforcement the typical fixed-ratio (“break-run”), fixed-interval (“scallop”), and multiple schedule response patterns were readily established and consistently maintained. With the imprinting stimulus these schedule effects were inconsistent in some subjects and virtually nonexistent in others, despite extended training. Schedule control with the imprinting stimulus was not improved by the use of a reinforcement signaling procedure which enhances responding reinforced by electrical brain stimulation on intermittent schedules. However, the overall rates of responding and the extinction functions generated after reinforcement with water versus the imprinting stimulus were comparable. These findings imply that control by temporal and discriminative stimuli may be relatively weak when a young organism's behavior is reinforced by presentation of an imprinting stimulus.     

Perceptual learning during filial imprinting: Evidence from transfer of training studies

Chicks were first imprinted by exposing them to a moving training stimulus, B or C, that was projected onto a screen at one end of an experimental cabinet. Subsequently, subjects selectively approached the stimulus to which they had been exposed. On the following day, the chicks were placed into a chilled experimental cabinet (15°C) and received trials on which two stimuli (A and B) were projected onto screens located at opposite ends of the cabinet. If the subject approached Stimulus A, a stream of warm air was delivered; if it approached B, the trial terminated, and no heat was presented. For subjects that had been imprinted with Stimulus B, those in Group B, Stimulus A was novel, and Stimulus B was familiar. For chicks that had been imprinted with Stimulus C, Group C, both A and B were novel. In two experiments, Group B acquired the discrimination more rapidly than did Group C. This observation, made using a novel training procedure, was taken to support the suggestion that imprinting results in a form of perceptual learning in which the familiar imprinting object has become more discriminable from other novel objects.     

An investigation into blocking of filial imprinting in the chick during exposure to a compound stimulus

The occurrence of "blocking" was investigated in jungle fowl chicks (Gallus gallus spadiceus B.) in an imprinting situation. In Experiment 1, chicks were simultaneously exposed to two stationary coloured cylinders, either two red cylinders (Group RR), a yellow and a red cylinder (YR), or two yellow cylinders (YY). After six days of exposure, the cylinders were removed from the cages and replaced by a yellow and a blue cylinder (i.e. YB) for each chick. This second phase of the experiment lasted for seven days. When the blue cylinder was presented alone during tests at different stages in Phase 2, the RR birds spent significantly more time with this cylinder and emitted fewer shrill calls than the chicks in the YR and YY groups. In Experiment 2, RR and YY birds were reared as in Experiment 1, except that in the second phase of the experiment they were exposed to a blue cylinder only. In this experiment the development of an attachment to the novel blue cylinder proceeded similarly in the RR and YY birds. In Experiment 3, it was found that chicks that were reared with a yellow and a red cylinder preferred the latter stimulus. Thus, although in the first phase of Experiment 1 the RR birds had been exposed to a more attractive stimulus, in tests during the second phase they spent more time with a novel stimulus (B) than the YY birds. These results are consistent with the suggestion that imprinting to a novel stimulus is "blocked" to some extent when that stimulus is presented in compound with another stimulus to which the animal has previously been exposed.     

Auditory basis of maternal attachment in ducklings (Anas platyrhynchos) under simulated naturalistic imprinting conditions

The presence of broodmates during the imprinting process results in peer imprinting that interrupts a visually mediated maternal attachment. We sought to determine the conditions in which group-trained mallard ducklings (Anas platyrhynchos) acquire a maternal attachment. At 48 hr of age, ducklings were allowed to follow a vocal, stuffed mallard hen individually or in groups of 4. Individual ducklings showed a preference for the silent, familiar mallard over an unfamiliar pintail. Ducklings trained in groups did not show a preference. When the mallard maternal call was present during testing, group-trained ducklings overwhelmingly responded to it regardless of whether it came from the familiar mallard or an unfamiliar pintail. Training ducklings in groups, which simulates the natural social context of imprinting, results in peer imprinting. Thus, early in development the young become visually imprinted to each other, and the maternal call mediates attachment to the mother.     

Development of neuronal responsiveness in the mediorostral neostriatum/hyperstriatum ventrale during auditory filial imprinting in domestic chicks

Chronic electrophysiological recordings of slow field potentials from tone-imprinted chicks show significantly enhanced fast Fourier transform (FFT) power during playback of rhythmic 400-Hz imprinting tone stimuli in the presence of a surrogate mother. The FFT power was already significantly higher during the very first imprinting session, when the chick was exposed to the imprinting tone stimuli in the presence of the surrogate mother compared to spontaneous activity (EEG recordings). During discrimination tests, where individual chicks were exposed to the imprinting tone stimuli in alternation to rhythmic 700-Hz tone stimuli (discrimination tone stimuli), the FFT power was significantly higher during playback of the imprinting tone stimuli than the FFT power during playback of the discrimination tone stimuli. Chicks which were imprinted in the absence of the surrogate mother also show enhanced FFT power in the course of the imprinting sessions; however, in contrast to the first group, they did not show significant differences in the FFT power during playback of either the imprinting or discrimination tone stimuli in the discrimination tests. Our results suggest that the high FFT power of a potential imprinting stimulus or situation, which is expressed in newborn (still naive) chicks, is maintained only when the chicks form an association between the tone stimuli and a positive emotional situation (represented by the surrogate mother).     

Frequency specific chromatic adaptation in the human visual system

Subjects were exposed to a vertical chromatic grating alternating with horizontal chromatic grating of the identical frequency. They were then tested with a series of test gratings of varied spatial frequencies to examine whether the responses were effected by the spatial frequency of the adaptation pattern in relation to the test pattern. It was found that maximum response occurred when adaptation and test gratings had the same spatial frequency, the effect was asymmetric and finally that enhancements were found at octaves. Thus the experiment further demonstrated that neural elements specific to spatial frequency exist in the human visual system.     

Mechanisms of visual threat detection in specific phobia

People with anxiety or stress-related disorders attend differently to threat-relevant compared with non-threat stimuli, yet the temporal mechanisms of differential allocation of attention are not well understood. We investigated two independent mechanisms of temporal processing of visual threat by comparing spider-phobic and non-fearful participants using a rapid serial visual presentation task. Consistent with prior literature, spider phobics, but not non-fearful controls, displayed threat-specific facilitated detection of spider stimuli relative to negative stimuli and neutral stimuli. Further, signal detection analyses revealed that facilitated threat detection in spider-phobic participants was driven by greater sensitivity to threat stimulus features and a trend towards a lower threshold for detecting spider stimuli. However, phobic participants did not display reliably slowed temporal disengagement from threat-relevant stimuli. These findings advance our understanding of threat feature processing that might contribute to the onset and maintenance of symptoms in specific phobia and disorders that involve visual threat information more generally.     

Locus of the effect of specific practice in continuous visual search

Specific practice in a visual search task can result either in a selective elaboration of the feature lists of the task stimuli or in a selective emphasis of their status within the task (targets vs. nontargets). According to the first explanation, which is related to the differentiation principle of perceptual learning, specific practice enhances the operation of stimulus identification. According to the second explanation, which is related to the enrichment principle of perceptual learning, it enhances the operation of response selection. Evidence from two transfer experiments with a reversal paradigm argues in favor of the second view, at least for tasks with easily codable letter stimuli. The results are discussed in the framework of a recent model of information integration in visual search.     

Role of visual information in ball catching

The present study is concerned with the perceptual information about the body and space underlying the act of catching a ball. In a series of four experiments, subjects were asked to catch a luminous ball under various visual conditions. In general, catching in a normally illuminated room was contrasted with catching the luminous ball in an otherwise completely dark room. In the third and fourth experiments, intermediate conditions of visual information were included. The results suggest that it is possible to catch a ball with one hand when only the ball is visible, but performance is better when the subject has the benefit of a rich visual environment and two hands. The second experiment indicated that subject performance does improve with practice in the dark, but time spent in the darkened room itself doesn't result in a significant decrement in performance. Results of the third study suggest that vision of one's hand does not aid in the performance of this task whereas the presence of a minimal visual frame appears to aid performance. The final study examined the relation between catching performance and body sway under similar visual conditions. Results of this experiment imply that persons who exhibit relatively little postural sway in full-room lighting performed better at this catching task.