Gaze following in the red-footed tortoise (Geochelone carbonaria)

Gaze following refers to the ability of an animal to orient its gaze direction to that of another organism. Such a behavior may be adaptive as it alerts the observer to important objects in the environment such as food or predators. This behavior has been shown in mammals and birds, but the evolutionary history and the distribution of this behavior throughout the animal kingdom remain unclear. Here, we show that a reptile, the red-footed tortoise (Geochelone carbonaria), is able to follow the gaze of a conspecific in a lookup task. Controls revealed that neither the mere presence of a conspecific nor the presentation of a light stimulus (without a demonstrator present) controlled the tortoises’ behavior. The findings indicate that the ability to follow gaze may be found in mammals, birds and reptiles and could have evolved before the amniotic line diverged, or may result from a general ability to learn.     

Spatial learning and memory in the tortoise (Geochelone carbonaria)

A single tortoise (Geochelone carbonaria) was trained in an eight-arm radial maze, with the apparatus and general procedures modeled on those used to demonstrate spatial learning in rats. The tortoise learned to perform reliably above chance, preferentially choosing baited arms, rather than returning to arms previously visited on a trial. Test sessions that examined control by olfactory cues revealed that they did not affect performance. No systematic, stereotyped response patterns were evident. In spite of differences in brain structure, the tortoise showed spatial learning abilities comparable to those observed in mammals.     

Visual and response-based navigation in the tortoise (Geochelone carbonaria)

Much research has investigated spatial cognition in mammals and birds. Evidence suggests that the hippocampus plays a critical role in this; however, reptiles do not possess a hippocampus. It has been proposed that the reptilian medial cortex plays a similar role, yet little behavioral research has directly investigated this. Consequently, this study examined the role of extramaze cues in spatial navigation by the red-footed tortoise (Geochelone carbonaria) using an eight-arm radial maze. In Experiment 1 the maze was surrounded by a black curtain on which geometrical shapes were attached. After the tortoise reached above-chance performance we introduced test sessions in which the cues were removed. Performance was unaffected by cue removal. The tortoise appeared to have developed a “turn-by-one-arm” strategy. In a second experiment the curtain was removed and the tortoise was allowed access to a rich-cue environment. The use of the turn-by-one-arm strategy was significantly reduced and the tortoise appeared to be using the extramaze cues to navigate around the apparatus. This type of response-based strategy, and the specific contexts in which it was used, has not been observed in mammals and birds, suggesting that the mechanisms served by the reptilian medial cortex do not parallel exactly those of the hippocampus.     

Molecular (moment-to-moment) and molar (aggregate) analyses of behavior

Ten meanings or usages of the terms molecular and molar analyses are based on (1) numbers of responses, (2) durations of activities, (3) levels, (4) scales, (5) contiguity versus correlation, (6) behavioral standards, (7) function with or without structure, (8) local versus global phenomena, and (9) control by shaping of sequential moment-to-moment behavior. These usages reveal divisive viewpoints along with ambiguities in the Law of Effect, the definition of an operant, response strength, response probability, random behavior, time allocation, shaping, controlled versus uncontrolled operants, and roles for ordinary language. Usage 10 is less divisive and combines, and in that sense unifies, molecular behavior, defined as shaped moment-to-moment sequential behaving, and molar, defined as averages of aggregates of those shaped responses. It combines shaping, that establishes and changes operant behaviors, and strengthening that changes the amounts of those shaped behaviors. I conclude that general behavioral theory will combine strengthening with such methods as parametric, hybrid, or nonparametric shaping, and will use computational methods to simulate moment-to-moment behavior streams from which any aggregates of theoretical interest may be computed. Such a synthesis may not require different levels, scales, or new scientific paradigms.     

Paternal behavior in the spiny mouse (Acomys cahirinus)

The responsiveness of adult male spiny mice (Acomys cahirinus) to both their own and alien precocial young was investigated. Paternal behavior was manifested primarily by the males huddling with their offspring and the coordination of pup attendance between adult males and females. With less than 2 days exposure to their own neonates, males were found to discriminate between their own and alien young. Experience plays an important role in the development of paternal behavior in spiny mice. Males who have never had pups of their own sniff and attack unfamiliar neonates more than males who have fathered pups. The adaptive significance of paternal investment in this uniquely precocial murid rodent was discussed.     

Factor analysis of the frontal systems behavior scale (FrSBe)

The Frontal Systems Behavior Scale (FrSBe), formerly called the Frontal Lobe Personality Scale (FLOPS), is a brief behavior rating scale with demonstrated validity for the assessment of behavior disturbances associated with damage to the frontal-subcortical brain circuits. The authors report an exploratory principal factor analysis of the FrSBe-Family Version in a sample including 324 neurological patients and research participants, of which about 63% were diagnosed with neurodegenerative diseases (Huntington's, Parkinson's, and Alzheimer's diseases). The three-factor solution accounted for a modest level of variance (41%) and confirmed a factor structure consistent with the three subscales proposed on the theoretical basis of the frontal systems. Most items (83%)from the FrSBe subscales of Apathy, Disinhibition, and Executive Dysfunction loaded saliently on three corresponding factors. The FrSBe factor structure supports its utility for assessing both the severity of the three frontal syndromes in aggregate and separately.     

A dialogue on Zeno's paradox of Achilles and the tortoise

The five participants in this dialogue critically discuss Zeno of Elea's paradox of Achilles and the tortoise. They consider a number of solutions to and restatements of the paradox, together with their philosophical implications. Among the issues investigated include the appearance-reality distinction, Aristotle's distinction between actual and potential infinity, the concept of a continuum, Cantor's continuum hypothesis and theory of transfinite ordinals, and, as a solution to Zeno's puzzle, the distinction between infinite and indeterminate or inexhaustible divisibility.