Motion leadership and local interaction in two species of freshwater fish (Danio rerio and Hyphessobrycon herbertaxelrodi).

The authors studied momentary motion leadership in small groups of black neon tetra (Hyphessobrycon herbertaxelrodi) and zebrafish (Danio rerio), its relationship with local interaction parameters, such as the acceleration and turning angle of the individuals, and the relative locations of the individuals within the group. The purpose was to know whether leadership tended to be monopolised by certain individuals or whether it was equitably shared between them and if there were differences in leadership sharing between these two species, which are known to have different degrees of cohesion and polarisation. The authors filmed groups of two, three, four and eight fishes of each species and tracked their individual motion by image analysis and trajectory extraction. In both species, motion leadership was not monopolized but egalitarian and very short lived, with leadership shifts distributed randomly over time. The duration of leadership episodes decreased as group size increased and was longer in black neon tetra than in zebrafish. Momentary leaders did not tend to be in the front positions, but closer to the centre of the group. Acceleration and turning angle were more extreme in zebrafish than in black neon tetra and in the momentary leaders than the followers in both species. In general, these differences between species and between leaders/followers were qualitatively similar with some differences in detail, indicating that the relationship between motion leadership and local interaction parameters is likely to conform to a general physical law.

Local interaction rules and collective motion in black neon tetra (Hyphessobrycon herbertaxelrodi) and zebrafish (Danio rerio).

We explored the local motion rules used by interacting individuals in small groups of black neon tetra (Hyphessobrycon herbertaxelrodi) and zebrafish (Danio rerio) to ascertain if and how these rules underlie the fishes' global collective coordinated motion. As these 2 species show very different styles of collective motion in terms of cohesion and polarization, we expected to find differences in their individual behavioral rules. We recorded groups of 2, 3, 4, and 8 fish of each species; tracked their individual trajectories; and studied how their individual turning angles and accelerations varied as a function of heading differences, distances, and relative angles to their neighbors. We found that black neon tetra and zebrafish differed in terms of their preferential positions with respect to their neighbors, the magnitude of turning angles and accelerations, and the way these angles and accelerations are modulated by both the distance from neighbors (thus suggesting a "repulsion" zone in black neon tetra but not in zebrafish) and the heading difference and relative angle to neighbors. Our results enable us to infer that, in black neon tetra, avoiding excessive proximity and collision takes priority over cohesion, and cohesion takes priority over polarization. This provides evidence that rules are similar in species of very different genera and that differences are a matter of degree. Our results also provide substantial empirical evidence to support the theoretical assumptions made in agent-based models that simulate coordinated collective motion in many different animal species. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Toothbrushing Systematics Index (TSI) - A new tool for quantifying systematics in toothbrushing behaviour.

Systematics is considered important for effective toothbrushing. A theoretical concept of systematics in toothbrushing and a validated index to quantify it using observational data is suggested. The index consists of three components: completeness (all areas of the dentition reached), isochronicity (all areas brushed equally long) and consistency (avoiding frequent alternations between areas). Toothbrushing should take a sufficient length of time; therefore, this parameter is part of the index value calculation. Quantitative data from video observations were used including the number of changes between areas, number of areas reached, absolute brushing time and brushing time per area. These data were fed into two algorithms that converted the behaviour into two index values (each with values between 0 and 1) and were summed as the Toothbrushing Systematics Index (TSI) value; 0 indicates completely unsystematic and 2 indicates perfectly systematic brushing. The index was developed using theoretical data. The data matrices revealed the highest values when all areas are reached and brushed equally long. Few changes occurred between the areas when the brushing duration was ≥90 s; the lowest values occurred under opposite conditions. Clinical applicability was tested with data from re-analysed videos from an earlier intervention study aiming to establish a pre-defined toothbrushing sequence. Subjects who fully adopted this sequence had a baseline TSI of 1.30±0.26, which increased to 1.74±0.09 after the intervention (p≤0.001). When the participants who only partially adopted the sequence were included, the respective values were 1.25±0.27 and 1.69±0.14 (p≤0.001). The suggested new TS-index can cover a variety of clinically meaningful variations of systematic brushing, validly quantifies the changes in toothbrushing systematics and has discriminative power.

Differences in shoaling behavior in two species of freshwater fish (Danio rerio and Hyphessobrycon herbertaxelrodi).

Fish can gain significant adaptive advantages when living in a group and they exhibit a wide variety of types of collective motion. The scientific literature recognizes 2 main patterns: shoals (aggregations of individuals that remain close to each other), and schools (aggregations of aligned, or polarized, individuals). We analyzed the collective motion of 2 social fish species, zebrafish (Danio rerio) and black neon tetra (Hyphessobrycon herbertaxelrodi), and compared their patterns of movement and the effect of group size and environmental constraints such as water column height and tank geometry on the collective motion of both species. We recorded the movement of groups of fish (n = 10 and n = 20) using 2 tank geometries: a rectangular shape and a rectangular shape with rounded corners; and we also manipulated the water column height (15 and 25 cm). We extracted the individual fish trajectories and calculated indices of cohesion, coordination, group density and group shape. The results showed that the 2 species had different types of collective motion: the zebrafish's global motion matched that of a shoal, while the black neon tetra's motion matched that of a school. Indirect evidence indicated that the 2 species tended to occupy the vertical space differently while swimming in a group. Finally, we found that tank geometry did not affect group polarization, whereas group size had an effect on black neon tetra density, which was higher in small group sizes than in large ones. (PsycINFO Database Record

Modelling the emergence of coordinated collective motion by minimizing dissatisfaction.

Coordinated collective motion (CCM) has been recently studied using agent-based simulations by applying three behavioural rules: repulsion, attraction and alignment. But these rules are so similar to the expected group behaviour that it can hardly be labelled emergent. We developed an agent-based model that produces CCM using a set of low-level dyadic interaction rules. The agents change their positions with regard to other agents in order to minimize their own dissatisfaction with their inter-individual distances. To test the emergence of CCM, several simulation experiments were performed. The results show that the agents were able to achieve CCM after a few thousand time steps, and that the bigger the area perceived by them, the more coordinated and cohesive the group motion became. An increased memory span and capacity to remember other agents' identities improved cohesion and coordination. The relationship with biological referents is discussed.

A method for resolving occlusions when multitracking individuals in a shoal.

Studying the collective behavior of fishes often requires tracking a great number of individuals. When many fishes move together, it is common for individuals to move so close to each other that some fishes superimpose themselves on others during one or several units of time, which impacts on tracking accuracy (i.e., loss of fish trajectories, interchange of fish identities). Type 1 occlusions arise when two fishes swim so near each other that they look like one long fish, whereas type 2 occlusions occur when the fishes' trajectories cross to create a T- or X-shaped individual. We propose an image processing method for resolving these types of occlusions when multitracking shoals in two dimensions. We assessed processing effectiveness after videorecording shoals of 20 and 40 individuals of two species that exhibit different shoal styles: zebrafish (Danio rerio) and black neon tetras (Hyphessobrycon herbertaxelrodi). Results show that, although the number of occlusions depended on both the number of individuals and the species, the method is able to effectively resolve a great deal of occlusions, irrespective of the species and the number of individuals. It also produces images that can be used in a multitracking system to detect individual fish trajectories. Compared to other methods, our approach makes it possible to study shoals with water depths similar to those seen in the natural conditions of the two species studied.

Determining shoal membership using affinity propagation.

We propose using the affinity propagation (AP) clustering algorithm for detecting multiple disjoint shoals, and we present an extension of AP, denoted by STAP, that can be applied to shoals that fusion and fission across time. STAP incorporates into AP a soft temporal constraint that takes cluster dynamics into account, encouraging partitions obtained at successive time steps to be consistent with each other. We explore how STAP performs under different settings of its parameters (strength of the temporal constraint, preferences, and distance metric) by applying the algorithm to simulated sequences of collective coordinated motion. We study the validity of STAP by comparing its results to partitioning of the same data obtained from human observers in a controlled experiment. We observe that, under specific circumstances, AP yields partitions that agree quite closely with the ones made by human observers. We conclude that using the STAP algorithm with appropriate parameter settings is an appealing approach for detecting shoal fusion-fission dynamics.

Determining shoal membership: a comparison between momentary and trajectory-based methods.

Miller and Gerlai proposed two methods for determining shoal membership in Danio rerio, one based on momentary mean inter-individual distances and the other on post hoc analysis of the trajectories of nearest-neighbor distances. We propose a method based on momentary nearest-neighbor distances and compare the three methods using simulation. In general, our method yielded results that were more similar to their second method than their first one, and is computationally simpler.

Factors affecting visual inference in single-case designs.

Visual inspection remains the most frequently applied method for detecting treatment effects in single-case designs. The advantages and limitations of visual inference are here discussed in relation to other procedures for assessing intervention effectiveness. The first part of the paper reviews previous research on visual analysis, paying special attention to the validation of visual analysts' decisions, inter-judge agreement, and false alarm and omission rates. The most relevant factors affecting visual inspection (i.e., effect size, autocorrelation, data variability, and analysts' expertise) are highlighted and incorporated into an empirical simulation study with the aim of providing further evidence about the reliability of visual analysis. Our results concur with previous studies that have reported the relationship between serial dependence and increased Type I rates. Participants with greater experience appeared to be more conservative and used more consistent criteria when assessing graphed data. Nonetheless, the decisions made by both professionals and students did not match sufficiently the simulated data features, and we also found low intra-judge agreement, thus suggesting that visual inspection should be complemented by other methods when assessing treatment effectiveness.

Factors Affecting Visual Inference in Single-Case Designs

Visual inspection remains the most frequently applied method for detecting treatment effects in single-case designs. The advantages and limitations of visual inference are here discussed in relation to other procedures for assessing intervention effectiveness. The first part of the paper reviews previous research on visual analysis, paying special attention to the validation of visual analysts’ decisions, inter-judge agreement, and false alarm and omission rates. The most relevant factors affecting visual inspection (i.e., effect size, autocorrelation, data variability, and analysts’ expertise) are highlighted and incorporated into an empirical simulation study with the aim of providing further evidence about the reliability of visual analysis. Our results concur with previous studies that have reported the relationship between serial dependence and increased Type I rates. Participants with greater experience appeared to be more conservative and used more consistent criteria when assessing graphed data. Nonetheless, the decisions made by both professionals and students did not match sufficiently the simulated data features, and we also found low intra-judge agreement, thus suggesting that visual inspection should be complemented by other methods when assessing treatment effectiveness (AU)

La inspección visual sigue siendo el método más utilizado para detectar tratamientos efectivos en diseños de caso único. El presente trabajo comenta las ventajas y limitaciones de la inferencia visual en relación con otros procedimientos empleados para evaluar la efectividad de las intervenciones. La primera parte del manuscrito revisa investigaciones previas sobre el análisis visual, enfocando la validación de las decisiones de los analistas visuales, la concordancia entre jueces y las tasas de falsas alarmas y omisión. Se hace énfasis en los factores que más afectan a la inspección visual (i.e., tamaño del efecto, autocorrelación, variabilidad en los datos y experiencia de los analistas) y éstos se incluyen en un estudio de simulación que pretende aportar evidencias sobre la calidad del análisis visual. Nuestros resultados coinciden con estudios previos sobre la relación entre la dependencia serial y un incremento en las tasas de error Tipo I. Los participantes con mayor experiencia parecen ser más conservadores y utilizan criterios más consistentes al evaluar datos gráficos. No obstante, tanto las decisiones de los profesionales y como las de los estudiantes no se corresponden lo suficiente con los datos simulados. Además, se encontró una baja consistencia intra-jueces, sugiriendo que la inspección visual se debería complementar por otros métodos a la hora de evaluar la efectividad de los tratamientos (AU)

Observer agreement for timed-event sequential data: a comparison of time-based and event-based algorithms.

Observer agreement is often regarded as the sine qua non of observational research. Cohen's kappa is a widely used index and is appropriate when discrete entities-such as a turn-of-talk or a demarcated time interval-are presented to pairs of observers to code. kappa-like statistics and agreement matrices are also used for the timed-event sequential data produced when observers first segment and then code events detected in the stream of behavior, noting onset and offset times. Such kappas are of two kinds: time-based and event-based. Available for download is a computer program (OASTES; Observer Agreement for Simulated Timed Event Sequences) that simulates the coding of observers of a stated accuracy and then computes agreement statistics for two time-based kappas (with and without tolerance) and three event-based kappas (one implemented in The Observer, one in INTERACT, and one in GSEQ). On the basis of simulation results presented here, and due to the somewhat different information provided by each, the reporting of both a time-based and an event-based kappa is recommended.

ACACIA: an agent-based program for simulating behavior to reach long-term goals.

We present ACACIA, an agent-based program implemented in Java StarLogo 2.0 that simulates a two-dimensional microworld populated by agents, obstacles and goals. Our program simulates how agents can reach long-term goals by following sensorial-motor couplings (SMCs) that control how the agents interact with their environment and other agents through a process of local categorization. Thus, while acting in accordance with this set of SMCs, the agents reach their goals through the emergence of global behaviors. This agent-based simulation program would allow us to understand some psychological processes such as planning behavior from the point of view that the complexity of these processes is the result of agent-environment interaction.

Random assignment of intervention points in two-phase single-case designs: data-division-specific distributions.

The present study explored the statistical properties of a randomization test based on the random assignment of the intervention point in a two-phase (AB) single-case design. The focus is on randomization distributions constructed with the values of the test statistic for all possible random assignments and used to obtain p values. The shape of those distributions is investigated for each specific data division defined by the moment in which the intervention is introduced. Another aim of the study consisted in testing the detection of inexistent effects (i.e., production of false alarms) in autocorrelated data series, in which the assumption of exchangeability between observations may be untenable. In this way, it was possible to compare nominal and empirical Type I error rates to obtain evidence on the statistical validity of the randomization test for each individual data division. The results suggest that, when either of the two phases has considerably fewer measurement times, Type I errors may be too probable and, hence, the decision-making process to be carried out by applied researchers may be jeopardized.

ActSds and OdfSds: programs for converting INTERACT and The Observer data files into SDIS timed-event sequential data files.

In this article, we describe programs for converting Mangold International's INTERACT and Noldus Information Technology's The Observer data files to sequential data interchange standard (SDIS) timed-event sequential data files. Users who convert their INTERACT or The Observer data files can then take advantage of various flexible and powerful data modification and computational procedures available in the Generalized Sequential Querier, a program that assumes SDIS-formatted files.

RAP: a computer program for exploring similarities in behavior sequences using random projections.

A computer program (RAP, for random projection) for exploring similarities between and within sequences of behavior is presented. Given a time window of a sequence, the program calculates a signature, a real-valued vector that is a random projection of the contents of the window (i.e., the codes occurring within it and their relative location, or onset and offset times) into an arbitrary K-dimensional space. Then, given two different time windows from the same sequence or from different sequences, their similarity is computed as an inverse function of the Euclidean distance between their respective signatures. By defining moving (overlapped or not overlapped) windows along each sequence and calculating similarities between every pair of windows from the two sequences, a map of similarities or possible recurrent patterns is obtained; the RAP program represents them as gray-level lattices, which are displayed as mouse-sensitive images in an HTML file. Computation of similarities is based on the random projection method, as presented by Mannila and Seppänen (2001), for the analysis of sequences of events. The program reads sequence data files in Sequential Data Interchange Standard (SDIS) format (Bakeman Quera, 1992,1995a).

Observer agreement for event sequences: methods and software for sequence alignment and reliability estimates.

When sequences of discrete events, or other units, are independently coded by two coders using a set of mutually exclusive and exhaustive codes, but the onset times for the codes are not preserved, it is often unclear how pairs of protocols should be aligned. Yet such alignment is required before Cohen's kappa, a common agreement statistic, can be computed. Here we describe a method--based on the Needleman and Wunsch (1970) algorithm originally devised for aligning nucleotide sequences--for optimally aligning such sequences; we also offer the results of a simulation study of the behavior of alignment kappa with a number of variables, including number of codes, varying degrees of observer accuracy, sequence length, code variability, and parameters governing the alignment algorithm. We conclude that (1) under most reasonable circumstances, observer accuracies of 90% or better result in alignment kappas of .60 or better; (2) generally, alignment kappas are not strongly affected by sequence length, the number of codes, or the variability in the codes' probability; (3) alignment kappas are adversely affected when missed events and false alarms are possible; and (4) cost matrices and priority orders used in the algorithm should favor substitutions (i.e., disagreements) over insertions and deletions (i.e., missed events and false alarms). Two computer programs were developed: Global Sequence Alignment, or GSA, for carrying out the simulation study, and Event Alignment, or ELign, a user-oriented program that computes alignment kappa and provides the optimal alignment given a pair of event sequences.

An index for quantifying flocking behavior.

One of the classic research topics in adaptive behavior is the collective displacement of groups of organisms such as flocks of birds, schools of fish, herds of mammals, and crowds of people. However, most agent-based simulations of group behavior do not provide a quantitative index for determining the point at which the flock emerges. An index was developed of the aggregation of moving individuals in a flock and an example was provided of how it can be used to quantify the degree to which a group of moving individuals actually forms a flock.

Physician-patient dialogue surrounding patients' expression of concern: applying sequence analysis to RIAS.

The aim of this study was to analyse with sequence analysis physician-patient dialogue surrounding patients' expression of emotional cues. Two samples, sample 1 consisting of 36 cancer patient consultations conducted by four oncologists, and sample 2 consisting 79 consultations of haematology patients conducted by nine specialists, were audiotaped and coded with the Roter Interaction Analysis System (RIAS). Sequence analysis by means of a generalized sequential querier (GSEQ) was applied to the coded data. Lag sequential analysis (analysed using RIAS categories) showed that certain behaviours of physicians corresponded with patients' expressions of concern. Physicians in both samples used silence and minimal encouragers before patient concern. The oncologists also used optimistic and affirming responses. The most common physician responses to patients' concern were minimal encouragers or affirming and optimistic responses. Sequence analysis based on RIAS coding appears to be a promising method for the study of doctor-patient dialogue and should be utilized more in studies of the communication process in medical consultations.

Exploring rare patient behaviour with sequential analysis: an illustration.

AIMS: To illustrate the application of sequence analysis to the study of rare patient behaviour in physician-patient dialogue. The rare behaviour in question here is patients' expression of emotional cues and concerns. We investigate which physician behaviours precede and follow such expressions. METHODS: Thirty-five cancer-patient consultations performed by four oncologists (two male and two female) were analysed. The consultations were coded with the Roter Interaction Analysis System (RIAS). Sequence analysis by means of Sequential Data Interchange Standard (SDIS) and the Generalized Sequential Querier (GSEQ) was applied to the coded data. Lag analysis (using RIAS categories) was applied to associate the given behaviour (patient 'concerns') with target behaviours (physician utterances). RESULTS: For female physicians the significantly associated behaviour before the patient's expression of concern was reassurance, while male physicians also applied facilitation behaviour. After patients' expression of concern both reassurance and facilitating behaviour were shown by physicians of both genders. CONCLUSIONS: Sequence analysis appears to be a clinically meaningful and statistically sound method for analysing are patient utterances and associated physician behaviour.

Efecto de autocorrelación sobre la tasa de error tipo I del estadístico Rn de Revusky: una simulación Monte Carlo / Autocorrelation effect on type I error rate of Revusky’s rn test: a Monte Carlo study

Mediante simulación Monte Carlo se analizan los efectos que la violación del supuesto de independencia provocan sobre la tasa de error Tipo I, en el estadístico Rn de Revusky. Los resultados de la simulación muestran la distorsión de la distribución de probabilidad del estadístico Rn cuando los datos presentan dependencia serial.Se propone y analiza una corrección del estadístico Rn que mitigue las diferencias entre los valores exactos y empíricos de la tasa de error Tipo I. Por sus favorables resultados recomendamos aplicar la corrección propuesta siempre que se sospeche de la existencia de dependencia serial en los datos (AU)