Invisible Displacement Tasks Research Articles

Pulling the wool over their eyes? Object permanence, numerical competence and categorisation in alternative livestock species

The adaptive abilities of grazing livestock species are not well understood, despite the potential link between behaviour driven decision making and the overall productive efficiency of the animal through foraging strategy. This study aimed to assess and compare these adaptive behaviours, relating to i) object permanence, ii) numerical competence, and iii) categorisation capabilities of domesticated species that possess distinctly different digestive physiologies and backgrounds. Seven animals from each species, including sheep (Ovis aries) (avg. 5 years of age, 60 kg initial weight), goats (Capra hircus) (avg. 3 years, 45 kg initial weight), and alpacas (Lama pacos (Linnaeus, 1758)) (avg. 3 years, 70 kg initial weight), were presented with a total of nine choice tasks, grouped relative to the three abilities being tested (object permanence, numerical competence, and categorisation). Specifically, the stage of object permanence for each subject was tested based on their ability to solve simple visible displacement, to overcome perseveration error, and double invisible displacement tasks. Subjects were also presented with a two-choice task of different open-centre and filled shapes to assess the capacity for simple discrimination and open-ended categorisation. Lastly, numerical competence was compared across five trials consisting of different ratios and volumes of food reward. A basic awareness of object permanence was found in all subjects. Overall, the goats demonstrated the greatest capacity for object permanence across the three species, particularly when presented with more complex three-cup A-not-B tasks. This increase in complexity had no significant effect on goat performance as a group (p = 0.13), whereas alpaca (p = 0.0005) and sheep performance significantly declined (p = 0.04). We also found no evidence to demonstrate contrasting cognitive capabilities between these species in relation to spontaneous numerical cognition (p > 0.05), or in the use of perceptual cues in open-ended categorisation (p = 0.246). This study is the first instance of multiple direct comparisons of cognitive capability across domesticated livestock species. Furthermore, this work is the first account of object permanence, numerical competence and categorisation in alpacas, as well as object permanence in sheep and numerical competence in sheep and goats. This information could prove useful to predict the outcome of interaction between these species in a grazing context and for inferences relating to behaviour driven decision making, such as foraging strategy, and the overall productive efficiency of the animal. Here, we conclude that the three species tested possess comparable capacity for physical cognition in the tasks discussed.

Horses' (Equus caballus) Ability to Solve Visible but Not Invisible Displacement Tasks Is Associated With Frustration Behavior and Heart Rate.

Many frameworks have assessed the ultimate and ontogenetic underpinnings in the development of object permanence, but less is known about whether individual characteristics, such as sex or training level, as well as proximate factors, such as arousal or emotional state, affect performance in these tasks. The current study investigated horses’ performance in visible and invisible displacement tasks and assessed whether specific ontogenetic, behavioral, and physiological factors were associated with performance. The study included 39 Icelandic horses aged 2–25 years, of varying training levels. The horses were exposed to three tasks: (a) a choice test (n = 37), (b) a visible displacement task (n = 35), and (c) an invisible displacement task (n = 31). 27 horses in the choice test, and 8 horses in the visible displacement task, performed significantly better than expected by chance, while none did so in the invisible displacement task. This was also reflected in their group performance, where horses performed above chance level in the choice task and the visible displacement task only. In the invisible displacement task, the group performed significantly worse than expected by chance indicating that horses persistently chose the side where they had last seen the target. None of the individual characteristics included in the study had an effect on performance. Unsuccessful horses had higher heart rate levels, and expressed more behavior indicative of frustration, likely because of their inability to solve the task. The increased frustration/arousal could lead to a negative feedback loop, which might hamper performance in subsequent trials. Care should thus be taken in future experimental designs to closely monitor the arousal level of the tested individuals in order to safeguard comparability.

El papel de la experiencia visual previa en el desarrollo de habilidades de permanencia de objetos en delfines nariz de botella (Tursiops truncatus)

La permanencia de los objetos, la capacidad de representar objetos ocultos, no se ha evaluado ampliamente en los cetáceos y la evidencia disponible es contradictoria. Aunque se cree que los delfines nariz de botella (Tursiops truncatus) están dotados de las capacidades cognitivas necesarias para aprobar pruebas complejas de permanencia de objetos, han fallado en una serie de tareas que involucran desplazamientos invisibles, lo que plantea la cuestión de si logran la permanencia de los objetos maestros. La falta de comprensión de la contención o la falta de experiencia en el seguimiento de objetos ocultos tanto de la vista como de la ecolocación pueden explicar estos resultados inesperados. El objetivo del presente estudio fue probar estas dos hipótesis en una serie de tareas de desplazamiento visibles e invisibles con delfines nariz de botella. Nuestros resultados sugieren que los delfines pueden tener éxito en tareas complejas de permanencia de objetos, pero solo si tienen experiencia visual previa con los movimientos de objetos dentro de otros objetos. Por lo tanto, estos resultados apuntan a un papel importante de la experiencia visual en el desarrollo de habilidades de permanencia de objetos.

Visible and invisible displacement with dynamic visual occlusion in bottlenose dolphins (Tursiops spp).

Anticipating the location of a temporarily obscured target-what Piaget (the construction of reality in the child. Basic Books, New York, 1954) called "object permanence"-is a critical skill, especially in hunters of mobile prey. Previous research with bottlenose dolphins found they could predict the location of a target that had been visibly displaced into an opaque container, but not one that was first placed in an opaque container and then invisibly displaced to another container. We tested whether, by altering the task to involve occlusion rather than containment, these animals could show more advanced object permanence skills. We projected dynamic visual displays at an underwater-viewing window and videotaped the animals' head moves while observing these displays. In Experiment 1, the animals observed a small black disk moving behind occluders that shifted in size, ultimately forming one large occluder. Nine out of ten subjects "tracked" the presumed movement of the disk behind this occluder on their first trial-and in a statistically significant number of subsequent trials-confirming their visible displacement abilities. In Experiment 2, we tested their invisible displacement abilities. The disk first disappeared behind a pair of moving occluders, which then moved behind a stationary occluder. The moving occluders then reappeared and separated, revealing that the disk was no longer behind them. The subjects subsequently looked to the correct stationary occluder on eight of their ten first trials, and in a statistically significant number of subsequent trials. Thus, by altering the stimuli to be more ecologically valid, we were able to show that the dolphins could indeed succeed at an invisible displacement task.

Double invisible displacement understanding in orangutans: testing in non-locomotor and locomotor space.

The nonadjacent double invisible displacement task has been used to test for the ability of different species to mentally represent the unperceived trajectory of an object. The task typically requires three occluders/boxes in a linear array and involves hiding an object in one of two nonadjacent boxes visited in succession. Previous research indicates that 19-, 26-, and 30-month-old children and various nonhuman species cannot solve these displacements. It has been hypothesized that this is because individuals are unable to inhibit searching in the unbaited center box that was never visited by the experimenter. It has been suggested that presenting the task in a large-scale locomotor space might allow individuals to overcome this inhibition problem. In the present study, we tested orangutans on adjacent and nonadjacent double invisible displacements with the traditional setup (experiment 1) and in locomotor space with boxes placed 1.22m apart (experiment 2). In both experiments, subjects were able to solve adjacent, but not nonadjacent, trials. The failure on nonadjacent trials appeared to be because of an inability to inhibit sequential search on the second choice as well as because of a large number of first-choice errors (directly choosing an incorrect box). The current results support previous findings that orangutans exhibit some constraints when representing the invisible trajectory of objects.

The use of a displacement device negatively affects the performance of dogs (Canis familiaris) in visible object displacement tasks.

Visible and invisible displacement tasks have been used widely for comparative studies of animals' understanding of object permanence, with evidence accumulating that some species can solve invisible displacement tasks and, thus, reach Piagetian stage 6 of object permanence. In contrast, dogs appear to rely on associative cues, such as the location of the displacement device, during invisible displacement tasks. It remains unclear, however, whether dogs, and other species that failed in invisible displacement tasks, do so because of their inability to form a mental representation of the target object, or simply because of the involvement of a more salient but potentially misleading associative cue, the displacement device. Here we show that the use of a displacement device impairs the performance of dogs also in visible displacement tasks: their search accuracy was significantly lower when a visible displacement was performed with a displacement device, and only two of initially 42 dogs passed the sham-baiting control conditions. The negative influence of the displacement device in visible displacement tasks may be explained by strong associative cues overriding explicit information about the target object's location, reminiscent of an overshadowing effect, and/or object individuation errors as the target object is placed within the displacement device and moves along a spatiotemporally identical trajectory. Our data suggest that a comprehensive appraisal of a species' performance in object permanence tasks should include visible displacement tasks with the same displacement device used in invisible displacements, which typically has not been done in the past.

Object permanence in the Goffin cockatoo (Cacatua goffini).

The ability to represent hidden objects plays an important role in the survival of many species. In order to provide an inclusive synopsis of the current benchmark tasks used to test object permanence in animals for a psittacine representative, we tested eight Goffin cockatoos (Cacatua goffini) on Stages 3-6 of Piagetian object permanence as well as derivations of spatial transposition, rotation, and translocation tasks. Subjects instantly solved visible displacement 3b and 4a but showed an extended plateau for solving Stage 5a at a very late age (10 months). Subjects readily solved most invisible displacement tasks including double hidings and four angles (90°, 180°, 270°, and 360°) of rotation and translocations at high performance levels, although Piagetian Stage 6 invisible displacement tasks caused more difficulties for the animals than transposition, rotations, and translocation tasks.

A note on pigs’ knowledge of hidden objects

Abstract. Object permanence is the notion that objects continue to exist even when they are out of observer´s sight. This ability is adaptive not only for free ranging animals who have to cope with a dangerous and highly changeable environment, allowing them to be aware of predators sneaking in their proximity or to keep track of conspecifics or food sources, even when out of sight. Farm animals, too, might profit from object permanence as the ability to follow the trajectory of hidden food or objects may lead to a higher predictability of subjects' environment, which in turn might affect the level of stress under husbandry conditions. We conducted two experiments to examine the ability of object permanence in young domestic pigs (Sus scrofa domestica). For this purpose we used a test setup that was formerly developed for primates and adopted it to the behavioural constraints of pigs. A rewarded object was hidden in one of three hiding locations with an increasing complexity of the objects movement through successive test sessions. Subjects were confronted with visible and invisible displacement tasks as well as with transpositions of hidden objects in different contextual settings. Pigs solved visible, but not invisible displacements or transpositions, indicating that they have difficulties to keep track of once hidden and then moved objects. This should be taken into account when designing husbandry environments or study designs.

Can Black‐and‐White Ruffed Lemurs (Varecia variegata) Solve Object Permanence Tasks?

We examined object permanence in black-and-white-ruffed lemurs (Varecia variegata) at Zoo Atlanta. A series of visible and invisible displacement tasks with suitable controls were presented to five adult subjects. Subjects performed significantly above chance on all regular tasks, except for the double invisible displacements. Subjects failed visible and invisible controls. Failure on the control trials did not appear to be because subjects used the "last box touched" strategy (subjects did not choose the last box touched significantly more than expected by chance). However, a substantial percentage of choices was made to the last box touched by the experimenter. There was no significant difference between this percentage, and the percentage of choices made to the baited box (on both visible and invisible controls), which indicates that subjects were drawn to both boxes which the experimenter visited/touched, and thus failed the controls. Based on the results from the present study, we believe that there is no evidence that black-and-white ruffed lemurs understand visible and invisible tasks in the traditional object permanence battery.

The role of testimony in young children's solution of a gravity-driven invisible displacement task

Previous research has shown that young children make a perseverative, gravity-oriented, error when asked to predict the final location of a ball dropped down an S-shaped opaque tube ( Hood, 1995). We asked if providing children with verbal information concerning the role that the tubes play, in determining the ball's trajectory would improve their performance. Experiment 1 showed that performance of 3.5-year-olds improved after hearing testimony about the movement of the ball. Experiment 2 showed that the specific content of the testimony – rather than any accompanying non-verbal cues – helped children improve. These findings suggest that other people's testimony can be a valuable source of information when young children learn about the physical world. Indeed, under some circumstances children seem to benefit more from verbal than visual information. An educational implication is that it may sometimes be ineffective to focus on the impact of first-hand experience while marginalizing the role of verbal information.

What do dolphins (Tursiops truncatus) understand about hidden objects?

Object permanence, the ability to mentally represent and reason about objects that have disappeared from view, is a fundamental cognitive skill that has been extensively studied in human infants and terrestrial animals, but not in marine animals. A series of four experiments examined this ability in bottlenose dolphins (Tursiops truncatus). After being trained on a "find the object" game, dolphins were tested on visible and invisible displacement tasks, and transpositions. In Experiments 1 and 2, dolphins succeeded at visible displacements, but not at invisible displacements or transpositions. Experiment 3 showed that they were able to pass an invisible displacement task in which a person's hand rather than a container was used as the displacement device. However, follow-up controls suggested they did so by learning local rules rather than via a true representation of the movement of hidden objects. Experiment 4 demonstrated that the dolphins did not rely on such local rules to pass visible displacement tasks. Thus, like many terrestrial animals, dolphins are able to succeed on visible displacement tasks, but seem unable to succeed on tasks requiring the tracking of hidden objects.

Do Dogs (Canis familiaris) Understand Invisible Displacement?

Domestic dogs (Canis familiaris) perform above chance on invisible displacement tasks despite showing few other signs of possessing the necessary representational abilities. Four experiments investigated how dogs find an object that has been hidden in 1 of 3 opaque boxes. Dogs passed the task under a variety of control conditions, but only if the device used to displace the object ended up adjacent to the target box after the displacement. These results suggest that the search behavior of dogs was guided by simple associative rules rather than mental representation of the object's past trajectory. In contrast, Experiment 5 found that on the same task, 18- and 24-month-old children showed no disparity between trials in which the displacement device was adjacent or nonadjacent to the target box.

Object permanence in common marmosets (Callithrix jacchus).

A series of 9 search tasks corresponding to the Piagetian Stages 3-6 of object permanence were administered to 11 common marmosets (Callithrix jacchus). Success rates varied strongly among tasks and marmosets, but the performances of most subjects were above chance level on the majority of tasks of visible and invisible displacements. Although up to 24 trials were administered in the tests, subjects did not improve their performance across trials. Errors were due to preferences for specific locations or boxes, simple search strategies, and attentional deficits. The performances of at least 2 subjects that achieved very high scores up to the successive invisible displacement task suggest that this species is able to represent the existence and the movements of unperceived objects.

A test of object permanence in a new-world monkey species, cotton top tamarins (Saguinus oedipus).

Cotton top tamarins were tested in visible and invisible displacement tasks in a method similar to that used elsewhere to test squirrel monkeys and orangutans. All subjects performed at levels significantly above chance on visible ( n=8) and invisible ( n=7) displacements, wherein the tasks included tests of the perseverance error, tests of memory in double and triple displacements, and "catch" trials that tested for the use of the experimenter's hand as a cue for the correct cup. Performance on all nine tasks was significantly higher than chance level selection of cups, and tasks using visible displacements generated more accurate performance than tasks using invisible displacements. Performance was not accounted for by a practice effect based on exposure to successive tasks. Results suggest that tamarins possess stage 6 object permanence capabilities, and that in a situation involving brief exposure to tasks and foraging opportunities, tracking objects' movements and responding more flexibly are abilities expressed readily by the tamarins.

What guides a search for food that has disappeared? Experiments on cotton-top tamarins (Saguinus oedipus).

When food is launched down a vertically positioned S-shaped opaque tube, cotton-top tamarins (Saguinus oedipus) search for the food in the position directly beneath the release point, even though over several trials it never appears in this position (B. M. Hood et al., 1999). Experiment 1 showed that when the trajectory of the food shifts from the vertical to the horizontal plane, tamarins no longer show systematic perseverative errors and, in general, perform better on this invisible displacement task. Experiment 2 showed that tamarins with experience on the horizontal task show less of a bias when tested on the vertical task but nonetheless fail overall to solve this invisible displacement problem; their performance is substantially worse than it was on the horizontal task. Experiment 3 revealed that when the vertically positioned tube is replaced by an occluded ramp, tamarins consistently search in the compartment below the release point, even though most of the tamarins had experience in Experiments 1 and 2. Overall, results indicate that tamarins have a significant gravity bias when searching for food that has disappeared along the vertical plane but also have more general problems finding food that has moved out of sight.

Distinguishing logic from association in the solution of an invisible displacement task by children (Homo sapiens) and dogs (Canis familiaris): Using negation of disjunction.

Distinguishing logic from association in the solution of an invisible displacement task by children (Homo sapiens) and dogs (Canis familiaris): Using negation of disjunction.

Development of object permanence in food-storing magpies (Pica pica).

The development of object permanence was investigated in black-billed magpies (Pica pica), a food-storing passerine bird. The authors tested the hypothesis that food-storing development should be correlated with object-permanence development and that specific stages of object permanence should be achieved before magpies become independent. As predicted, Piagetian Stages 4 and 5 were reached before independence was achieved, and the ability to represent a fully hidden object (Piagetian Stage 4) emerged by the age when magpies begin to retrieve food. Contrary to psittacine birds and humans, but as in dogs and cats, no "A-not-B error" occurred. Although magpies also mastered 5 of 6 invisible displacement tasks, evidence of Piagetian Stage 6 competence was ambiguous.

Can memory requirements account for species' differences in invisible displacement tasks?

Can memory requirements account for species' differences in invisible displacement tasks?

Gravity does rule for falling events

Hood (1995) reported a vertical invisible displacement task where the goal was to find a ball that was dropped down one of three chimneys connected to three hiding boxes below by opaque tubes. Preschool children exhibited perseverative search at the box directly below the chimney where the ball was dropped even though the tubes were always visible and the children were given numerous trials and feedback. This behavior was interpreted as a naive theory of gravity. The current study set out to test the naive gravity theory hypothesis by reversing the motion of the event on a television. On half of the trials the object appeared to fall up the tube into one of the boxes which were now on the top of the apparatus. There were significantly more errors for ‘down’ trials as compared to ‘up’ trials which supports the hypothesis that children are biased to infer that falling objects travel in a straight line whereas anti‐gravity events do not conform to this naive theory.

Specific Cognitive Abilities in 2-Year-Old Children with Subependymal and Mild Intraventricular Hemorrhage

Subependymal and mild intraventricular hemorrhages (S/IVH) are likely to affect the subcortical and frontal cortex regions of the brain in premature infants. Damage to the subcortical and frontal areas has been associated with poorer performance in certain abilities, including visual attention, memory for location, and ability to change response set. This study investigated whether S/IVH, occurring at birth, affect these abilities in young children. Two-year-old premature children with S/IVH, premature children with normal neonatal head ultrasound scans, and full term children with normal births were evaluated on a series of tasks. These tasks were a habituation/novelty preference task (visual attention), Piaget's invisible displacement task (memory for location), an object discrimination reversal task (ability to change response set), and the Bayley Scales of Infant Development (traditional infant test). Premature children with hemorrhage performed significantly less well on the task of ability to remember the last location of a hidden object and on the task of ability to reverse response set. Both groups of premature children performed significantly less well than full term children on systematic search for an object once the order of hiding was reversed. There were no significant differences among the three groups on the habituation/novelty preference task or on Bayley scores. Results suggest that both S/IVH and prematurity affect development of specific cognitive abilities.