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.

Horses’ (Equus caballus) performance in visible and invisible displacement tasks is expressed in 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 investigated 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 showed 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 hamperperformance 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.

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 ‘‘objectpermanence’’—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.

Experimental and Numerical Investigation of Resonance Characteristics of Novel Pumping Element Driven by Two Piezoelectric Bimorphs

This paper describes the vibration characteristics of a dual-bimorph piezoelectric pumping element under fluid–structure coupling. Unlike the single bimorph used in most previous studies, the proposed device comprises two piezoelectric bimorphs within an acrylic housing. Amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) was used to examine the visible displacement fringes in order to elucidate the anti-phase as well as in-phase motions associated with vibration. Analysis was also conducted using impedance analysis and laser Doppler vibrometer (LDV) based on the measurement of point-wise displacement. The experimental results of resonant frequencies and the corresponding mode shapes are in good agreement with those obtained using finite element analysis. The gain of flow rate obtained by the anti-phase motion of the dual-bimorph pumping element is larger than both those obtained by in-phase motion and the single bimorph pumping element. This work greatly enhances our understanding of the vibration characteristics of piezoelectric pumping elements with two bimorphs, and provides a valuable reference for the further development of bionic pump designs.

Cognitive Understanding of Object Permanence in Mandrills (Mandrillus sphinx, L.)

Object permanence tests are a standard procedure to test the cognitive ability to mentally follow a hidden object. To test this capacity in mandrills, we used visible and color-tracking with invisible displacement tests. During visible displacement the object was hidden and moved within its container in full view of the tested individual. During color-tracking with invisible displacement the object was hidden in a colored container, also in full view, but then moved within its container out of view. The tested mandrills were successful in the visible but not in the color-tracking with invisible displacement tests. They did not use the color as a cue for the correct container. One of the animals memorized the position of the container, in which the reward was dropped before the invisible displacement. We assume that the capacity of solving invisible displacement tests has evolved after the evolutionary separation of mandrills and apes.

When pigeons in motion lose sight of their food: behaviour on visible displacement tasks revisited

In traditional visible displacement tasks, animals view an object as it is moved out of their sight, but either the object moves behind an occluder or an occluder moves in front of it. Here we present a more ecologically realistic visible displacement task for pigeons ( Columba livia (Gmelin, 1789)) in which it was the animal that occluded the object, a food dish in this case, by virtue of its own motion. In a branched maze, pigeons had visual access to food, which they would lose from view as they moved through the maze. A within-subject design was used whereby the task was presented first in descending order of difficulty (i.e., decreasing memory load owing to the opening of (i) gaps and (ii) windows in the walls of the maze), and followed 10 months later by an ascending order. When the food was visible at all times through windows and gaps, pigeons would make turns in the maze that would bring them closer to the food (i.e., they chose the shortest route above chance levels). In general, they failed to do so when the food was lost from view, but there was one exception at the end of the study (the second time that there were gaps but no windows): there was a significant tendency for the last two turns that brought the bird out of the maze to be the shortest route to the food. The pigeons may have learned to take advantage of opportunities to lighten their memory load.

Cognitive bases of lexical development: object permanence and relational words

ABSTRACTThe hypothesis that there is a close relationship between object permanence and early language acquisition has not been supported by most previous research. McCune-Nicolich (1981), however, performed a detailed theoretical analysis and, as a result, found a close relationship between stage 6 object permanence development and the use of relational words. Unlike previous studies which used mostly quantitative measures of language, McCune-Nicolich related object permanence to the semantic content of the child's early words. She concluded that relational words enter the child's lexicon ‘as a group’ during stage 6, due in part to the development of the cognitive abilities of that stage. The current study attempts to make this claim more specific and consequently more accurate. Relational words requiring the conceptualization of the visible displacement of objects should emerge during stage 5, those involving invisible displacements during stage 6, and those referring to more complex spatial displacements only later during the pre-operational period. Data from a longitudinal study of six 1-year-olds corroborate this more specific account.