Fundamental questions in cognitive science concern the origins and nature of the units that compose visual experience. Here, we investigate the capacity to individuate and store information about non-solid portions, asking in particular whether free-ranging rhesus monkeys ("Macaca mulatta") quantify portions of a non-solid substance presented in…

A robust finding in humans and animals is that intermixed exposure to 2 similar stimuli (AX/BX) results in better discriminability of those stimuli on test than does exposure to 2 equally similar stimuli in 2 separate blocks (CX_DX)--the intermixed-blocked effect. This intermixed-blocked effect may be an example of the superiority of spaced over…

The present studies examined whether the retrieval of an old "reactivated" memory could be brought under the control of new contextual cues. In Experiment 1 rats trained in one context were exposed to different contextual cues either immediately, 60 or 120 min after a cued reactivation of the training memory. When tested in the shifted context,…

We describe the construction and operation of three low-cost schlieren imaging systems that can be fabricated using surplus optics and 80/20, an aluminium extrusion based construction system. Each system has a different optical configuration. The low cost and ease of construction makes these systems highly suitable for high-school and…

The present article deals with the problem of combined harvesting of a Michaelis-Menten-type ratio-dependent predator-prey system. The problem of determining the optimal harvest policy is solved by invoking Pontryagin's Maximum Principle. Dynamic optimization of the harvest policy is studied by taking the combined harvest effort as a dynamic…

People know little about the non-domesticated animals that live around them. Somehow, they seem remote. In stories they hear about them, animals are often acting, speaking, and dressing like people. This article presents a lesson where students learn about the native species of their area while exploring the concept of interdependence through…

Learning strategy selection was assessed in two different inbred strains of mice, C57BL/6 and DBA/2, which are used for developing genetically modified mouse models. Male mice received a training protocol in a water maze using alternating blocks of visible and hidden platform trials, during which mice escaped to a single location. After training,…

In the past few months, animal-rights groups have stepped up their demonstrations against academic researchers who use animals, spawning a new wave of concern among scientists. In February, extremists caused a fire at the home of a researcher from the University of California at Los Angeles, and protesters struck the husband of a scientist from…

To test the hypothesis that social rearing may induce malleability, socially reared and socially isolated mallard duck, Anas platyrhynchos, embryos and hatchlings were exposed to the maternal call of a chicken, Gallus gallus domesticus, until 48 h after hatching. The hatchlings were then tested with the chicken call versus the mallard maternal…

Rhesus monkeys were trained and tested in visual and auditory list-memory tasks with sequences of four travel pictures or four natural/environmental sounds followed by single test items. Acquisitions of the visual list-memory task are presented. Visual recency (last item) memory diminished with retention delay, and primacy (first item) memory…

Information that is spaced over time is better remembered than the same amount of information massed together. This phenomenon, known as the spacing effect, was explored with respect to its effect on learning and neurogenesis in the adult dentate gyrus of the hippocampal formation. Because the cells are generated over time and because learning…

One conditioned taste aversion experiment with rats assessed the impact of extinguishing a target conditioned stimulus (CS), S, in compound with a second CS, A, upon conditioned responding elicited by CS S when presented alone at test. Following initial conditioning treatment with CSs A and S, the experiment manipulated number of extinction trials…

Gilbert Gottlieb was an elegant experimentalist whose research was inspired in part by naturalistic observations of parent-offspring vocal-auditory interactions of waterfowl. Such observations are essential in identifying potential linear (obvious) as well as nonlinear (subtle) mechanisms underlying the development of species-typical behavior. His…

Two experiments with rats examined the effects of context extinction on responding to the signal value of an unconditioned stimulus (US). In Experiment 1, US signal value was first trained when a single food pellet signaled the delivery of three additional pellets. After training, rats received either context extinction (CE) or home cage (HC)…

Of all animal-rights issues, medical research is perhaps the thorniest. The human use of animals--for companionship, entertainment, food, clothing--always assumes a hierarchy, one that puts humans at the top or the center of either the evolutionary order, God's creation, or the food chain. Although most people can come to terms with the use of…