On the utility of aPost Hoc correction procedure for one-zero sampling duration estimates

Numerous previous studies have shown that one-zero sampling in direct observation systematically overestimates behavioral durations. Apost hoc correction procedure has been proposed and demonstrated to be capable of removing most of the systematic errors found in one-zero duration estimates. However, the remaining errors for some individual observation sessions can still be quite substantial in practical terms. In this paper, the condition under which thepost hoc correction procedure will produce results with negligible systematic errors in one-zero duration estimates is identified.     

An empirical comparison of one-zero,focal-animal,and instantaneous methods of sampling spontaneous primate social behavior

InJ. Altmann's review of methods used to sample spontaneously occurring social behavior, the one-zero method, which has a history of over 40 years of use with human and animal research, was severely criticized and was the only technique for which no use whatsoever was recommended. Substantial justification for this recommendation would raise serious questions about widely cited primate research from laboratories at Cambridge, Wisconsin, and elsewhere, where one-zero sampling has been often used.Altmann's nonempirical consideration of one-zero sampling is based upon assumptions which are sometimes unnecessarily limiting or probably incorrect and which are not supported by any data. An empirical comparison of one-zero sampling with two techniques considered useful byAltmann reveals contradictions in her recommendations and suggests that the one-zero method is a convenient way to combine the actual rate and duration of a spontaneously occurring behavior into a single index of social relatedness.     

An empirical evaluation of instantaneous and one-zero sampling of chimpanzee behavior

The behavior category in progress at theend of every 15 seconds of observation of chimpanzee behavior was recorded (instantaneous sampling) as was the occurrence or nonoccurrence of all defined categoriesduring every 15 second observation interval (one-zero sampling). The scores obtained using the above procedures were then correlated with the percent of net observation time, hourly rate, and mean bout duration of the behavior categories. One-zero sampling scores correlated very strongly with percent of net observation time and moderately with hourly rate and mean bout duration. Instantaneous sampling scores correlated very strongly with percent of net observation time and moderately with hourly rate and mean bout duration.     

Properties of one-zero scores in observational studies of primate social behavior: The effect of assumptions on empirical analyses

Empirical analyses of techniques for observing spontaneous social behavior have been guided by implicit assumptions about the techniques’ validity, reliability, and comparability. The actual duration and actual frequency of a behavior have been used as intuitive standards of validity. Noncorrespondence among absolute values obtained from these measures and from one-zero scores has been taken to mean that one-zero scores are invalid. An analysis of macaque and gelada grooming relationships demonstrated how unjustified assumptions about absolute values can affect conclusions. A statistical comparison of four types of observation scores, and a multiple-regression analysis of one-zero scores, contradicted assumptions made previously about reliability and validity. The four methods were comparable and all were reasonably accurate.     

Effects of Temporal Sampling Patterns of All-occurrence Recording in Behavioural Studies: Many Short Sampling Periods Are Better than a Few Long Ones

All-occurrence recording is generally thought to yield unbiased results. However, its accuracy and power to detect real effects may depend on the temporal patterning of the observation periods. Although several studies evaluated the suitability of time-sampling methods (one-zero and instantaneous sampling), there has not been an evaluation of various temporal patterns of the ‘all-occurrence’ method to date. Here we present an empirical comparison of time-sampling and all-occurrence recording methods, based on a large data set, with special reference to various temporal patterns of all-occurrence recording. The three different sampling methods were imposed on raw data protocols. The scores, obtained by the use of each method and temporal pattern, were compared with true values from the corresponding continuous video recordings. The accuracy and power of each method was estimated by comparison of medians and magnitudes of effect (r_m), respectively. We were able to confirm results of earlier studies on the suitability of time-sampling methods (one-zero and instantaneous sampling), but we found that different temporal patterns of all-occurrence sampling yielded magnitudes of effect that differed from true value magnitudes. We conclude that behavioural studies may reveal different results, even when all conditions are the same, only because of power differences of different temporal pattern of the observation periods, for example 1 × 15 min versus 15 × 1 min. Recommendations are made about appropriate application of methods.     

Weaning of free-ranging infant baboons (Papio cynocephalus) as indicated by one-zero and instantaneous sampling of feeding

Weaning from the nipple and the use of solid foods were studied by one-zero and instantaneous sampling during the first year of life for 46 baboon infants. By the end of 1 year, infant baboons were nearing independence from the mother for nourishment and transportation and were competently foraging for insects and several plant foods. Using on-nipple as an index of waning dependence and the transition from riding on the mother to walking as a validity criterion, the two sampling methods yielded comparable scores which were valid indicants of developing independence.     

Effects of combination birth control on estrous behavior in captive western lowland gorillas, Gorilla gorilla gorilla

Combination birth control pills (CBC) are one of the most common birth control methods used for western lowland gorillas (Gorilla gorilla gorilla) housed in zoos. Since zoos are interested in maintaining as many natural behaviors as possible, it is important to know how contraception may affect social and sexual interactions among group members. Although some data are available regarding the influence of the pill on sexual behavior in human females, no data are available on its effects on gorilla estrous behavior. We examined temporal trends of estrous, aggressive, affiliative, and activity budget data in four females on CBC at the Lincoln Park Zoo in Chicago, IL. Behavioral data were collected using point sampling, all-occurrence records, and one-zero sampling. Estrous behavior occurred in less than 1% of observations. Using all-occurrence and one-zero sampling, estrous behavior occurred more frequently in week one of the cycle than any other week. The focal females exhibited affiliative, aggressive, and activity budget data evenly across their cycles. There were also no temporal trends in proximity to the silverback. Females varied by the types of estrous behavior they exhibited. We give a hormonal explanation for the prevalence of estrous behaviors in week one, and recommendations for effective behavioral sampling of gorilla estrous behavior.     

Fast activation of a time-dependent outward current in protoplasts derived from coats of developing Phaseolus vulgaris seeds

An outward current that appeared to activate instantaneously in response to depolarising voltage pulses at low sampling frequencies predominated in the plasma membrane of ground-parenchyma protoplasts derived from coats of developing Phaseolus vulgaris L. (cv. Redland Pioneer) seeds. However, the outward current showed time-dependent activation when higher sampling frequencies were used to measure the current. Activation of the current was best described as a double-exponential time course with the fast and slow time constants being 1 and 20 ms, respectively. The current also exhibited a rapid deactivation that followed a double-exponential time course with time constants of approximately 2 and 30 ms, respectively. “Tail-current” analysis allowed us to show that this current exhibited a low selectivity between K⁺ and Cl⁻ (P _K:Cl=1.8). Such a fast-activating current may account for some of the reports of time-independent, instantaneous currents that have been observed in plasma membranes of plant cells digitised at low sampling frequencies. Therefore, when “instantaneous” currents appear it is advisable to characterise these currents using higher sampling frequencies with correspondingly higher filtering frequency cut-offs. Received: 12 May 2000 / Accepted: 26 June 2000     

Comparison of instantaneous and locomotor bout sampling methods: a case study of adult male chimpanzee locomotor behavior and substrate use.

Currently two methods, instantaneous and locomotor bout sampling, are used most commonly in studies of locomotor behavior. To date, no study has addressed how comparable the results of the two methods are. This paper considers whether different sampling methods of locomotor behavior produce different results. Continuous locomotor bout and instantaneous sampling were carried out simultaneously on each focal animal during a seven month study of chimpanzee positional behavior in the Tai Forest of the Ivory Coast. Results provide two independent sets of data which describe the same events. Results indicate that as locomotor bouts are frequently presented (the percentage of bouts spent in an activity), they overrepresent the frequencies of activities that occur relatively often, but for short distances, and underrepresent activities that have a relatively large mean distance per bout. However, when bouts are weighted with distance, as originally defined by Fleagle (1976b), there are no significant differences in the results obtained by the two methods. Both provide similar results for the frequencies of locomotor activities, frequency of substrate use, and the relationship between substrate and locomotor activity. The advantage of instantaneous sampling is that because it is done at regular intervals, it can easily be carried out in conjunction with sampling other behavioral and ecological data. The advantages of locomotor bout sampling are that it permits the sampling of rare or brief locomotor events and allows for an analysis of sequences of locomotor activities. This paper demonstrates that the two methods can be conducted simultaneously and thus provide the richest return from which the effect of environment and morphology on locomotion can be addressed.     

Short Time Scale Changes in Underwater Irradiance in a Wind-exposed Lagoon (Vaccarès Lagoon,France): Efficiency of Infrequent Field Measurements of Water Turbidity or Weather Data to Predict Irradiance in the Water Column

High frequency water sampling in the wind-exposed Vaccarès lagoon revealed frequent and rapid changes in suspended solid (SS) concentrations in the water column. SS concentrations, sometimes higher than 800 mg l⁻¹, were significantly correlated with antecedent wind conditions. Mean wind velocity during the 5–33 h before water sampling or maximal wind velocity during the previous 8.5–22 h were good predictors of SS concentrations in the water column. Underwater irradiance at canopy level was modeled (r² = 0.66, n = 7584) using the SS calculated from the relationship between SS and antecedent mean wind velocity and the surface irradiance data measured at the weather station close to the study site. On the other hand, we have shown that in this wind-exposed lagoon, mean underwater irradiance can not be effectively estimated using infrequent measurements of the optical properties of water.     

Loud calls ofGalago crassicaudatus andG. garnettii and their relation to habitat structure

Long distance vocalizations have been shown to be good indicators of genetic species in primates. Here the loud calls of two recently identified greater galago taxa —Galago crassicaudatus andG. garnettii — are compared and analyzed statistically. Observed differences in call structures are investigated further as potential indicators of differences in the structures of habitats frequented by the two species. Although the calls share a repetitive structure, and show similar dominant frequency bands (1,000 – 1,500 Hz), they differ significantly in the number of units per call, unit duration, inter-unit interval, highest frequency, lowest frequency, dominant frequency band, first harmonic, and call duration. The duration of theG. crassicaudatus call is more than twice that ofG. garnettii. Strong intraspecific consistency is seen in the most energetic frequency bands (dominant frequency band and first harmonic), and durations of the individual units and inter-unit intervals. Information important to species recognition is thus most likely to be contained in these features. Individual recognition may be encoded in the relative emphasis of higher level harmonics. The frequency structures of the calls will reflect requirements for acoustical transmission in a forest environment, as well as structural constraints imposed by body size. Higher frequencies detected in theG. garnettii call (up to 8,500 Hz) may have a functional significance related to distance estimation, or may simply be a reflection of smaller body size. The greater modulation of theG. garnettii call suggests that its habitat constitutes a denser or more turbulent medium for sound transmission than does the habitat ofG. crassicaudatus.     

Response time and threshold of a random net

The response time of a random net is defined as the expected time (measured in the number of synaptic delays) required for the excitation in the net (measured by the fraction of neurons firing per unit time) to reach a certain level. The response time is calculated in terms of the net parameters as a function of the intensity of the outside stimulation. Two principal types of cases are studied, 1) an instantaneous initial stimulation, and 2) continuously applied stimulation. It is shown that for a certain type of net where the required level of excitation is small, the response time-intensity equation reduces to the one derived on the basis of the “one-factor” theory applied to a neural connection. More general assumptions, however, give different types of equations. The concept of the “net threshold” is defined, and its calculation indicated. The net threshold for instantaneous stimulation is, in general, greater than that for continuous stimulation. The results are discussed with reference to existing theories of reaction times.     

A comparison of resonance tuning with positive versus negative sensory feedback

We used a computational model of rhythmic movement to analyze how the connectivity of sensory feedback affects the tuning of a closed-loop neuromechanical system to the mechanical resonant frequency (ω_r). Our model includes a Matsuoka half-center oscillator for a central pattern generator (CPG) and a linear, one-degree-of-freedom system for a mechanical component. Using both an open-loop frequency response analysis and closed-loop simulations, we compared resonance tuning with four different feedback configurations as the mechanical resonant frequency, feedback gain, and mechanical damping varied. The feedback configurations consisted of two negative and two positive feedback connectivity schemes. We found that with negative feedback, resonance tuning predominantly occurred when ω_r was higher than the CPG’s endogenous frequency (ω_CPG). In contrast, with the two positive feedback configurations, resonance tuning only occurred if ω_r was lower than ω_CPG. Moreover, the differences in resonance tuning between the two positive (negative) feedback configurations increased with increasing feedback gain and with decreasing mechanical damping. Our results indicate that resonance tuning can be achieved with positive feedback. Furthermore, we have shown that the feedback configuration affects the parameter space over which the endogenous frequency of the CPG or resonant frequency the mechanical dynamics dominates the frequency of a rhythmic movement.     

“Ignition” phenomena in random nets

The spread of excitation in a “random net” is investigated. It is shown that if the thresholds of individual neurons in the net are equal to unity, a positive steady state of excitation will be reached equal to γ, which previously had been computed as the weak connectivity of the net. If, however, the individual thresholds are greater than unity, either no positive steady state exists, or two such states depending on the magnitude of the axone density. In the latter case the smaller of the two steady states is unstable and hence resembles an “ignition point” of the net. If the initial stimulation (assumed instantaneous) exceeds the “ignition point,” the excitation of the net eventually assumes the greater steady state. Possible connections between this model and the phenomenon of the “preset” response are discussed.     

High-resolution time-series data for 1991/1992 primary production and related parameters at a Palmer LTER coastal site: implications for modeling carbon fixation in the Southern Ocean

 Our goal was to provide a high-resolution temporal data base for modeling primary production in shelf waters adjacent to Palmer Station, Antarctica. Here, the resulting 1991/1992 data base is used to: (1) determine in situ productivity over a range of seasonal to subseasonal time scales; (2) identify time scales of significant variability in marine productivity during the peak growing season; (3) identify environmental, experimental and analytical factors that can significantly impact the accuracy of daily, weekly and seasonal productivity estimates; and (4) integrate our findings with previous studies of Antarctic coastal primary pro- duction. Data were gathered every 2–3 days during a 3-month period in the austral spring/summer of 1991/1992. Photosynthesis-irradiance (P-I) relationships were determined throughout the euphotic zone and P-I parameters, combined with knowledge of the in-water light field, were used to derive instantaneous rates of in situ primary production. Additionally, weekly samples were collected from surface and chlorophyll a maxima for characterization of the patterns of diel periodicity in P-I parameters. Seven diel patterns were discerned over the season and used to time-correct instantaneous measurements and derive noontime, daily, monthly and seasonally integrated estimates of production. During the season, a large bloom was responsible for some of the highest daily produc- tivity rates reported for the Southern Ocean (0.8 g C m^-3 d^-1, 6.3 g C m^-2 d^-1). Significant variation in daily integrated rates occurred generally on time scales less than a week. Peak timing and magnitude of daytime periodicities in photosynthesis varied widely over the season, closely coupled to changes in phytoplankton community composition. Instantaneous measurements of primary production, if uncorrected or improperly corrected for daytime periodicities in carbon fixation, were unreliable predictors of production on longer time scales even if the water column was sampled every few days. High frequency sampling and consideration of diel periodicity may be requirements when attempting to discern differences between short time-scale variability and long-term trends in Antarctic primary production. Received: 9 October 1995/Accepted: 18 February 1996     

Activity budget of inshore Indo‐Pacific bottlenose dolphins (Tursiops aduncus): A critical evaluation of methods and comparison among other populations

Activity budgets are widely used to compare behavior patterns but sampling methods vary, rendering comparisons difficult. The two main methods used are instantaneous and continuous sampling. Their comparability was examined by applying them to data obtained from bottlenose dolphins in the Port River estuary, South Australia. They gave comparable results for activity budgets, but instantaneous sampling did not detect most of the behavioral events. Individual differences in behavior and/or follow duration influenced results. Variability in activity definitions and categories among studies makes comparative analysis difficult. Comparison of the Port River dolphin's activity budget with other inshore populations indicated the former spent more time feeding and resting, and less time traveling. The greater feeding time seemed to be due to small prey size rather than reduced abundance or unpredictable distribution. The reduced traveling time, possibly the result of low predation pressure and/or evenly distributed prey, gave them more time to rest. They traveled mostly at 2.5 kn or less, consistent with studies from other shallow areas. Most feeding was individual, probably on demersal species. Surface feeding incorporated physical barriers rather than cooperative behavior. Activity durations ranged from 2 s to 2.9 h, with mean durations varying from 7.8 to 22.9 min.     

Light environment and carbon gain of understory herbs associated with sunflecks in a warm temperate deciduous forest in Japan

Seasonal variation in the light environment on the forest floor of a deciduous forest was investigated with special reference to sunflecks. Diurnal variations and seasonal changes in frequency and irradiation period of the sunflecks (sunfleck duration) were measured. The hourly total sunfleck duration varied seasonally; that is, 30–40 min in spring and autumn and about 15–20 min in summer. There was no large variation in the hourly sunfleck duration during daytime hours (from 9.00 to 15.00 h). The emergence frequency of sunflecks was 1.3–4.8 per h with two peaks, one in the morning and one in the afternoon. The mean duration of a sunfleck, however, showed a characteristic daily pattern with a peak around noon. Sunfleck duration was long around noon, ranging from 12 to 18 min, and short around 10.00 and 14.00 h, ranging from 6 to 10 min. Using the light photosynthesis curves ofPyrola japonica andSyneilesis palmata (Koizumi & Oshima 1985), the contribution of sunflecks to the dry matter production of these understory species was evaluated. It was shown that the sunflecks contributed 7–10% of the carbon gain inS. palmata, but only 2–3% of that inP. japonica.     

Assessing diversity of arbuscular mycorrhizal fungi in a local community: role of sampling effort and spatial heterogeneity

Diversity of arbuscular mycorrhizal fungi (AMF) was assessed in two 9.2 × 9.2-m plots planted with landscape trees and shrubs at an experimental site in Phoenix, AZ, USA. Twenty-five soil samples were collected in a regular grid pattern from each plot, and AMF species were identified using trap cultures. A total of 12 species were detected, with 7 species detected in one plot and 11 in the other. We found that sampling effort had a major impact on assessing species richness and composition in this local community. Fifteen samples would be necessary to detect 70–80% of species present in each plot. A limited number of additional undetected species are likely to be present in both plots, based on the sampling effort curves and jackknife estimates. Only two species, Glomus eburneum and Glomus microaggregatum, were detected in over 50% of the samples from both plots, and rank–frequency plots revealed a lognormal species distribution. Despite the patchiness of plants in the plots, the number of species detected per point exhibited spatial structuring only at the smallest sampling scale in a single plot, and only a single species in each plot was not randomly distributed. These results indicate that sampling effort and strategy can affect perceptions of AMF community structure.     

Detection of sinusoidal gratings by pattern-specific detectors: further evidence for the correlation principle in human vision

 The detection of compound sinusoidal gratings of various spatial frequency separations and four different grating sizes has been studied using the summation-to-threshold paradigm. Contrast interrelation functions have been measured and spatial frequency tuning estimates, based on the slope of the contrast interrelation function at two definite points, were derived using the “negative gradient technique” proposed by Logvinenko [Logvinenko (1995) Biol Cybern 73: 547–552]. It is shown that compound grating detection can be modelled by assuming pattern-specific sensory mechanisms for each of the spatial frequency components, which adapt to the periodicity and the size of the stimulus but not to its envelope function. Further, it is shown that relative sensitivity for a given spatial frequency separation can be predicted with good accuracy by the correlation of the grating components used for superposition. It is suggested that the most plausible implementation of the pattern correlation principle in human grating detection is the “grating cell” model. Received: 10 March 2000 / Accepted in revised form: 4 December 2000     

Changes in gape frequency, siphon activity and thermal response in the freshwater bivalves Anodonta cygnea and Margaritifera falcata

Physiologically-driven rhythms in bivalve molluscs are predictedto vary as a function of metabolic rate and temperature, incontrast to genetically predisposed biological clocks. Theserhythms can be evaluated using long-term video monitoring techniquesunder controlled conditions in laboratory aquaria. The bivalvesAnodonta cygnea and Margaritifera falcata were used to evaluatethe effect of temperature on rhythms in gape and the formationof siphons at the mantle edge. Frequency and duration of shellclosure vary with temperature in both species, but with differentresponses. Mean duration of intervals of valve closure decreasesas temperature rises in both species, and is consistent withphysiological limitation by increased biological oxygen demand.For A. cygnea, cumulative gape duration peaks at 25°C, withless time spent closed than at any other temperature, but increasingtemperatures correspond to an increase in gape frequency witha strong increase observed at 31°C. In contrast, frequencyof adduction and valve closure peak at 25°C in M. falcata,and continuous gaping is observed above 29.5°C. This physiologicalstress is consistent with evidence from sclerochronologically-calibratedstable isotope studies of shells, where growth breaks in manymarine taxa coincide with maximum temperatures above 31°Cas derived for ¹⁸O_carbonate. The results of this study suggestthat these growth breaks may be due to physiological limitationsin oxygen uptake and metabolic activity, rather than being adirect consequence of elevated temperature alone. (Received 17 March 2008; accepted 3 October 2008)