Maternal territoriality as an offspring defense strategy in red swamp crayfish (Procambarus clarkii,Girard)

The offspring‐defense hypothesis of maternal territoriality in solitary and semisocial mammals [Wolff JO and Peterson JA. 1998. Ethol Ecol Evol 10:227–239] was evaluated in another taxon using maternal and nonmaternal female red swamp crayfish (Procambarus clarkii), a freshwater decapod crustacean that shows pronounced shelter‐related maternal aggression. The maternal females were of three different categories: (1) ovigerous, (2) carrying primarily stage 1 offspring, or (3) tending offspring that were primarily stage 2. Each female was in residence in an individual aquarium containing only a gravel substrate for 24 hr prior to serial intrusions by male conspecifics. Virtually all of the residents, maternal and nonmaternal, excavated a depression (shelter) in the substrate prior to the first intrusion. The results showed that residents in each of the maternal categories won a significantly higher proportion of their encounters than did the nonmaternal residents, which showed only negligible defense and lost every encounter. However, there were no significant differences in encounter outcomes between the maternal resident categories. There was clear defense of the shelter by maternal females, with virtually all fighting being in or around it, thus demonstrating stable, heightened territorial defense throughout these maternal phases of reproduction. This support of the offspring‐defense hypothesis of maternal territoriality is the first such evidence for a freshwater crustacean and is very similar to that recently reported in a related marine decapod, the American lobster (H. americanus). Aggr. Behav. 27:391–403, 2001. © 2001 Wiley‐Liss, Inc.     

Sample size determination for at test given at value from a previous study: A FORTRAN 77 program

When uncertain about the magnitude of an effect, researchers commonly substitute in the standard sample-size-determination formula an estimate of effect size derived from a previous experiment. A problem with this approach is that the traditional sample-size-determination formula was not designed to deal with the uncertainty inherent in an effect-size estimate. Consequently, estimate-substitution in the traditional sample-size-determination formula can lead to a substantial loss of power. A method of sample-size determination designed to handle uncertainty in effect-size estimates is described. The procedure uses thet value and sample size from a previous study, which might be a pilot study or a related study in the same area, to establish a distribution of probable effect sizes. The sample size to be employed in the new study is that which supplies an expected power of the desired amount over the distribution of probable effect sizes. A FORTRAN 77 program is presented that permits swift calculation of sample size for a variety oft tests, including independentt tests, relatedt tests,t tests of correlation coefficients, andt tests of multiple regressionb coefficients.     

Counseling for loss of faith

Pastoral Psychology -     

Book reviews

Schulkin, J. (1991). Sodium hunger: The search for a salty taste. Cambridge: Cambridge University Press. Pp. 192. ISBN 0-521-35368-8. £30.00 (hardback).

Heiligenberg, W.F. (1991). Neural nets in electric fish. Cambridge, MA: MIT Press (A Bradford Book). Pp. 179. ISBN 0-262-08203-9. £33.75 (hardback).

Donald, M. (1991). Origins of the modern mind: Three stages in the evolution of culture and cognition. Cambrdige, MA: Harvard University Press. Pp. 413. ISBN 0-674-64483-2. £22.25 (hardback).     

A developmental sequence in preschool children's acquisition of reading readiness skills and print awareness concepts

While various attempts have been made to explain the relationships among preschool children's acquisition of various aspects of print-related knowledge, studies have generally employed statistical procedures appropriate for linear relationships. Yet the relationships among measures of print-related knowledge may not be linear. One technique that has not been employed in this area but which provides a means for identifying nonlinear hierarchical relationships among measures is order analysis. The purpose of this paper was to examine empirically the acquisition of preschool children's print-related knowledge through order analysis. A data set that consisted of 60 preschool children's performances on five measures which assessed concepts about the purposes and processes of reading and the reading readiness skills of letter naming and visual and auditory discrimination was reanalyzed using ordering procedure. A multivariate analysis indicated a multidimensional relationship among the three reading readiness and two print awareness measures that differed across the three age groups. The hierarchical orderings of the five measures indicated that mastery of the reading readiness skills occurred prior to the mastery of the print awareness concepts.     

The timing of shifts of head postures during conservation

The timing of shifts of head postures in relation to speech during conservation was investigated by continuously monitoring, with a polarised light goniometer, the head movement of four subjects engaged in conservation.Postural shifts (PSs), defined as wide, linear movements, were found to occur primarily towards the initiation of speech, be it between speaking turns, or between syntactic boundaries inside speaking turns. This suggested that PSs are involved in regulating turn taking and marking syntactic boundaries inside speaking turns.Also, PSs usually started prior to and continued till after speech onset. This suggested a possible involvement in speech production, probably in helping to regulate the complex motor processes of beginning to speak.It is suggested that interactive, linguistic and speech productive functions may combine together to create a movement pattern by mutually constraining head movement.     

Use of an ambiguous-sample procedure to establish a cue to forget in pigeons

Pigeons were trained on a variation of the matching-to-sample task in which on double-sample trials two samples, one associated with each of the comparison stimuli, were presented successively. Responding to the comparison associated with the first sample was reinforced on half the double-sample trials, and responding to the comparison associated with the second sample was reinforced on the remaining half. One of two postsample stimuli was presented following the termination of each colored sample. A vertical line was presented after a correct or target sample, and a horizontal line was presented after an incorrect or interfering sample. With extended training, each bird demonstrated above-chance accuracy on double-sample trials, providing prima facie evidence that one or both of the postsample stimuli exerted control over matching behavior. Experiment 2 provided evidence that the horizontal line functioned as a cue to forget the code activated by the preceding sample stimulus. It was concluded that a condition sufficient to establish a postsample stimulus as a cue to forget is that the postsample immediately follow presentation of a sample that, if it were to control test responding, would lead to nonreinforcement.     

The possible interaction of Harderian material and saliva for thermoregulation in the Mongolian gerbil, Meriones unguiculatus

Self-grooming in Meriones unguiculatus is associated with saliva spread and the release and spread of Harderian material from the external nares. Saliva spread results in evaporative cooling and Harderian spread insulates the pelage. Two experiments tested the predictions that (1) saliva production and Harderian material decrease systematically following a self-groom, (2) high ambient temperature (34 degrees C) increases saliva production but decreases Harderian release, and (3) low ambient temperature (7 degrees C) decreases saliva production but increases Harderian release. The predictions were generally confirmed, suggesting that short-term and long-term thermoregulatory reactions are differentially affected by ambient temperatures. Thus, an animal will tend to emphasize saliva production when evaporative cooling is needed and will exaggerate Harderian release when insulation of the pelage is required.