Trajectories Of Aggression Research Articles

Heterogeneous Trajectories of Parental Psychological Aggression from Middle Childhood to Early Adolescence in China: Associations with Child- and Family-Level Predictors and Children's Developmental Outcomes.

Previous research has shown that parental psychological aggression may change with children's age, and individual differences existed in the developmental trajectories of parental psychological aggression within different families. However, most studies on the heterogeneous psychological aggression trajectories have focused solely on mothers or combined mothers' and fathers' data, with few studies separately exploring the unique trajectories of fathers and mothers and their predictors and outcomes within Chinese societies. Therefore, this study investigated the heterogeneous trajectories of paternal and maternal psychological aggression from middle childhood to early adolescence and their associations with child- and family-level predictors and outcomes in China. A total of 1137 Chinese families with children in grades 1-3 (Mage = 7.17; SDage = 0.95 at Time 1; 52.35% boys, 47.65% girls) participated in assessments at five time points, using 1-year internals in between. Latent class growth models were used to estimate the heterogeneous trajectories of paternal and maternal psychological aggression from ages 7 to 11 years. Logistic regression analyses were used to understand the child- and family-level predictors of these trajectories, and analysis of covariance was used to examine the outcomes of these trajectories. The findings revealed that three trajectories of paternal psychological aggression were identified: low-persistent (88.95%), high-decreasing (7.93%), and high-increasing-decreasing (3.12%) trajectories. Four trajectories of maternal psychological aggression were identified: low-persistent (86.17%), high-decreasing (5.94%), high-increasing-decreasing (4.08%), and low-increasing (3.81%) trajectories. Lower marital satisfaction, more psychological aggression experiences during childhood, and being a parent of a boy were risk factors for both paternal and maternal trajectories, while higher negative affectivity in children was a risk factor of maternal but not paternal trajectories. In addition, the high-increasing-decreasing trajectory for both fathers and mothers as well as the low-increasing trajectory for mothers predicted children's more internalizing and externalizing problems. These findings highlight the importance of considering heterogeneity in understanding the developmental patterns of parental psychological aggression, their predictors, and cumulative effects on child development.

Disease-modifying treatment and disability progression in subclasses of patients with primary progressive MS: results from the Big MS Data Network

BackgroundEffectiveness of disease-modifying treatment (DMT) in people affected by primary progressive multiple sclerosis (PPMS) is limited. Whether specific subgroups may benefit more from DMT in a real-world setting remains unclear....

Aggressive and robust low-level control and trajectory tracking for quadrotors with deep reinforcement learning

Aggressive and robust low-level control and trajectory tracking for quadrotors with deep reinforcement learning

Modeling trajectories of physical aggression from infancy to pre-school age, their early predictors, and school-age outcomes.

This study identified latent trajectories of physical aggression (TPA) from infancy to preschool age and evaluated (a) effects of early parent, parenting and child predictors on TPA as well as on social, behavioral, and academic functioning in Grade 2, and (b) TPA effects net of early predictor effects on Grade 2 functioning. We used data from the Behavior Outlook Norwegian Developmental Study (BONDS), which included 1,159 children (559 girls). Parents reported on risk and protective factors, and on physical aggression from 1 to 5 years of age; teachers reported on Grade 2 outcomes. We employed latent class growth curve analyses and identified nine TPA. In fully adjusted models simultaneously testing all associations among predictors, trajectories, and outcomes, maternal and paternal harsh parenting, child gender, and sibling presence predicted TPA, which significantly predicted externalizing and academic competence in Grade 2. Child gender had a pervasive influence on all outcomes as well as on TPA. To our knowledge, this is the first trajectory study to determine which predictors are most proximal, more distal, or just confounded, with their relative direct effect sizes, and to link early paternal as well as maternal harsh parenting practices with children's TPA. Our findings underscore the need to include fathers in developmental research and early prevention and intervention efforts.

Optimization-Based Control for a Large-Scale Electrical Vertical Take-Off and Landing during an Aircraft’s Vertical Take-Off and Landing Phase with Variable-Pitch Propellers

The UAV industry has witnessed an unprecedented boom in recent years. Among various kinds of UAV platforms, the vertical take-off and landing (VTOL) aircraft with fixed-wing configurations has received more and more attention due to its flexibility and long-distance flying abilities. However, due to the fact that the advance ratio of regular propeller systems during the cruise phase is significantly higher than that during the VTOL phase, a variable-pitch propeller system is proposed and designed which can be applied without additional propulsion mechanisms during both flying stages. Thus, a VTOL aircraft platform is proposed based on the propulsion system constructed of variable-pitch propellers, and appropriate control manners are precisely analyzed, especially during its VTOL phase. As a basic propulsion system, a nonlinear model for variable-pitch propellers is constructed, and an optimization-based control allocation module is developed because of its multi-solution and high-order characteristics. Finally, the objective function is designed according to the stability and energy consumption requirements. Simulation experiments demonstrate that the proposed controller is able to lower energy consumption and maintain the stability of the aircraft while tracking aggressive trajectories for large-scale VTOLs with noises at the same time.

A quasi-experimental study in sibling dyads: differential provocation-aggression patterns in the interactive taylor aggression paradigm.

The Taylor Aggression Paradigm (TAP) is a well-established tool for assessing provocation-induced reactive aggression. We introduce an interactive version, the iTAP, with real-time opponents across 60 trials, including five simulated provocation trials in the middle. In this quasi-experimental study, we evaluate the effectiveness of the paradigm to investigate reactive aggression in interacting participants. The design allows us to employ the TAP in settings of high familiarity dyads, addressing an existing gap. Twenty-eight healthy same-sex adult sibling pairs (N = 56) competed against each other in the iTAP, exemplifying high familiarity through their social and emotional co-development, and mutual knowledge. Additionally, we explore naturally arising aggression types in terms of sibling pairs' reciprocal aggression trajectories across trials. Lastly, we investigate situational and personal variables influencing reactive aggression on the iTAP within high familiarity dyads. In line with non-interactive TAP versions, siblings employed a global "tit-for-tat" strategy in response to heightened provocation: Aggression increased during manipulated trials of increasing provocation, persisted during real interaction and declined in the final block, suggesting sibling co-regulation which was underscored by the convergence in within-pair aggression level. We found no gender differences in these dynamics but a trend for higher initial aggression levels within brother pairs and higher responsiveness to increased provocation in sister pairs. Overall aggression levels were related to situational variables including trial outcome (lost, won, and tie), Further, siblings' state anger correlated positively with aggression scores on the iTAP. Aggression was not reliably related to personal variables predicting aggression. We identified subgroups of sibling pairs with distinct provocation-aggression patterns related to differences in reported behavioral motivations and emotional states. The results highlight situational over personal variables in determining aggressive behavior on the task in this sample of healthy adults. While no direct link between sibling relationship quality and aggression was found, the overall behavior was likely influenced by the familiarity between siblings and the specific context of their relationship. The iTAP demonstrates promise as a tool for studying reciprocal aggressive behavior. The emergence of different interaction patterns underscores the ecological validity introduced by the interactive context, which complements the standard versions of the TAP.

Hitchhiker: A Quadrotor Aggressively Perching on a Moving Inclined Surface Using Compliant Suction Cup Gripper

Perching on the surface of moving objects, like vehicles, could extend the flight time and range of quadrotors. Suction cups are usually adopted for surface attachment due to their durability and large adhesive force. To seal on a surfaces, suction cups must be aligned with the surface and possess proper relative tangential velocity. However, quadrotors’ attitude and relative velocity errors would become significant when the object surface is moving and inclined. To address this problem, we proposed a real-time trajectory planning algorithm. The time-optimal aggressive trajectory is efficiently generated through multimodal search in a dynamic time-domain. The velocity errors relative to the moving surface are alleviated. To further adapt to the residual errors, we design a compliant gripper using self-sealing cups. Multiple cups in different directions are integrated into a wheel-like mechanism to increase the tolerance to attitude errors. The wheel mechanism also eliminates the requirement of matching the attitude and tangential velocity. Extensive tests are conducted to perch on static and moving surfaces at various inclinations. Results demonstrate that our proposed system enables a quadrotor to reliably perch on moving inclined surfaces (up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.07m/s$</tex-math> </inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$90^\circ$</tex-math> </inline-formula> ) with a success rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$70\%$</tex-math> </inline-formula> or higher. The efficacy of the trajectory planner is also validated. Our gripper has larger adaptability to attitude errors and tangential velocities than conventional suction cup grippers. The success rate increases by 45% in dynamic perches. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper was motivated by the problem of perching on moving inclined surfaces using quadrotors. It can be used for perching on the various angled surfaces of an automobile to save energy and enlarge flight distance. It can also be exploited in air-ground cooperative tasks. In recent years, various grippers and trajectory planning methods have been devised to enable quadrotors to perch on static inclined surfaces. These strategies can not be used for perching on moving inclined surfaces. The task poses high requirements for the efficiency of trajectory planning and the grippers’ adaptability to pose errors. This paper proposes a real-time planning method to generate trajectories. The trajectories respect kinematic and motor lift constraints. They allow large attitude maneuvering of quadrotors. A multimodal search in a dynamic time-domain is developed to seek the minimum feasible time for the trajectory planner. Considering large pose errors in dynamic perching, a compliant gripper based on multiple independent suction cups is designed. The wheel and multidirectional layout of cups increase the adaptability to attitude and velocity errors. Results suggest that the proposed system is effective and reliable. In practice, our multiple cups would add weight penalty and increase the drag. The suction cups should be placed close to a quadrotor’s central axis to reduce the drag and disturbance in flow. The proposed system relies on an external motion capture system. In future research, we will focus on onboard sensing and control methods to achieve perching on moving inclined surfaces outdoors.

Aggression and Irritability in Middle Childhood: Between- and Within-Person Associations

ABSTRACT Objective This study tested predicted bidirectional associations between irritability and physical and relational forms of aggression, disentangling theorized within- and between-person effects using latent curve models with structured residuals (LCM-SR) over one year in middle childhood. Gender differences and robustness of results when controlling for other externalizing problems (i.e., attention problems, delinquency) were also considered. Method Children in third, fourth, and fifth grade (N = 704, 49.9% female) were recruited from schools in a large midwestern city. The sample was diverse in regard to race/ethnicity (31% Black, 29% White, 13% Hmong, 14% Latinx, 4% Native American, 4% Asian, 5% other races/ethnicities). Irritability, attention problems, and delinquency were measured using teacher-report, and physical and relational aggression were measured using self-report at three time points over one calendar year. Results At the between-person level, higher mean levels of irritability predicted higher initial levels of physical and relational aggression. Irritability continued to predict higher levels of physical aggression across the course of the study, whereas the effect of irritability on relational aggression diminished. Boys showed higher starting levels of physical aggression, but no other significant gender differences emerged. No significant within-person associations were found. Conclusions The present study suggests that irritability may represent a between-person risk factor for high levels of physical and relational aggression in middle childhood, although effects on physical aggression may be more persistent. This highlights the importance of considering affective processes to understand the development of aggression trajectories.

A numerically-stable trajectory generation and optimization algorithm for autonomous quadrotor UAVs

This paper introduces a novel trajectory generation and optimization algorithm (TGO) that enables agile and aggressive flight of quadrotor UAVs while considering various constraints associated with robot dynamics, actuator inputs, and flight environment. The TGO algorithm employs time-parametrized polynomial trajectories based on a predetermined sequence of waypoints to produce dynamically feasible and collision-free trajectories. This approach extends previous work that utilized differential flatness property and polynomial based trajectories by eliminating the need for iterative searching and computationally intensive sampling. One of the significant advantages of the TGO algorithm is its numerical stability for large number of waypoints and high-order polynomials. To address the ill-conditioned problem of Quadratic Programming (QP) based methods, the TGO algorithm reformulates the trajectory generation and optimization problem into an unconstrained quadratic programming (UCP) using the numerically stable null-space factorization method. The TGO algorithm produces minimum derivative trajectories and minimum waypoints arrival times, generating a wide range of aggressive trajectories that can leverage the full maneuvering capabilities of quadrotor robots. The proposed algorithm’s numerical stability and computational advantages are demonstrated through various scenarios and comparisons. An animated simulation of the TGO algorithm is available at: https://youtu.be/MvvhBG14iIg.

On-Manifold Model Predictive Control for Trajectory Tracking on Robotic Systems

Model predictive control (MPC) has the ability to incorporate state and input constraints and extendability to systems with multiple inputs and outputs, making it a popular technique for robot control and other real-world applications. However, robotic systems usually evolve on manifolds, which are often over-parameterized or minimally parameterized (but with singularity) in a MPC. How to naturally incorporate the system manifold constraints without over-parameterization or singularity is a fundamental problem when deploying MPC on robotic systems. In this paper, we propose a unified on-manifold MPC framework to address the mentioned issue. This framework first formulates the MPC based on a canonical representation of on-manifold systems. Then, the on-manifold MPC formulation is solved by linearizing the system at each point along the trajectory under tracking. There are two main advantages of the proposed scheme. The first is that the linearized system leads to an equivalent error system represented by a set of minimal parameters without any singularities. Secondly, the process of system modeling, error-system derivation, linearization and control has the manifold constraints completely decoupled from the system descriptions, enabling to develop a symbolic MPC framework that naturally encapsulates the manifold constraints. In this symbolic framework, one need only to supply system-specific descriptions without dealing with the manifold constraints. To validate the generality of the proposed framework, we implement it on two different robotic platforms, a quadrotor unmanned aerial vehicle (UAV) evolving on a Lie group, and an unmanned ground vehicle (UGV) moving on a curved surface with non-Lie group structure. To validate the non-singularity and tracking performance of the framework, we test it in tracking aggressive UAV trajectories. Experimental results show that with a single, global on-manifold MPC controller, the quadrotor tracks highly aggressive trajectories with large actuator efforts and attitude variation (360 degrees) in both roll and pitch directions, without controller switching.

A Robust Disturbance-Rejection Controller Using Model Predictive Control for Quadrotor UAV in Tracking Aggressive Trajectory

A robust controller for the waypoint tracking of a quadrotor unmanned aerial vehicle (UAV) is proposed in this paper, in which position control and attitude control are effectively decoupled. Model predictive control (MPC) is employed in the position controller. The constraints of motors are imposed on the state and input variables of the optimization equation. This design effectively mitigates the nonlinearity of the attitude loop and enhances the planning efficiency of the position controller. The attitude controller is designed using a nonlinear and robust control law based on SO(3) space, which enables continuous control on the SO(3) manifold. By extending the differential flatness of the quadrotor-UAV to the angular acceleration level, the mapping of the control reference from the position controller to the attitude controller is achieved. Simulations are carried out to demonstrate the capability of the proposed controller. In the simulations, multiple aggressive flight trajectories and severe external disturbances are designed. The results show that the controller is robust, with superior accuracy in tracking aggressive trajectories.

The buildup to the National Security Law in Hong Kong: From Structural Contradictions to Direct Violence

The political scene of Hong Kong both before and after the transition from British to Chinese authority was one of negative calm - the absence of violence. Sino-British Joint Declaration (1984), for instance, &amp; a mini-constitution (i.e., Basic Law) picturing the city's future under the People's Republic of China were to guarantee the public's autonomy in politics and social rights. Nevertheless, Hong Kong's political context evolved from poor peace (with the Joint Declaration providing a foundation for positive peace) to indirect and ultimately direct violence. The writings that envisioned "a substantial amount of autonomy" and "democratization" were riddled with inconsistencies and contradictions. The rise of the National Security Act continued this aggressive trajectory, in which underlying conflicts created cycles of continual violence that were originally entrenched in structure but became explicitly evident at a level of mindset and subsequently conduct after 2014.

Developmental trajectories of aggression, hyperactivity/inattention, and anxious depressed mood: co-occurring problems within a chilean context

AbstractThe current study examined multi-trajectories of aggression, hyperactivity/inattention and anxious/depressed problems, along with associated risk factors for trajectory group membership, using a person-centred approach. The sample included 2,857 children (50.1% males) enrolled in the Chilean Encuesta Longitudinal de la Primera Infancia cohort. Maternal reports using the Child Behaviour Checklist (CBCL) were completed when children were three, five and eleven years old. Information on risk/protective factors was collected using maternal reports and standardised assessments when children were aged three. Group-based multi-trajectory analysis was implemented. Results indicated that a five-group model best fit the data, with co-occurring symptoms across domains for all groups. Risk factors for membership of groups with the most elevated risk profiles included child sex, maternal age, single parent status, and maternal education, whilst children’s receptive language, maternal vocabulary skills, and not having early attendance in the educational system emerged as protective factors. These identified risk factors may be important targets for future intervention programmes in the Chilean context.

Proactive and reactive aggression: Developmental trajectories and longitudinal associations with callous-unemotional traits, impulsivity, and internalizing emotions.

Research on proactive and reactive aggression has identified covariates unique to each function of aggression, but hypothesized correlates have often not been tested with consideration of developmental changes in or the overlap between the types of aggression. The present study examines the unique developmental trajectories of proactive and reactive aggression over adolescence and young adulthood and tests these trajectories' associations with key covariates: callous-unemotional (CU) traits, impulsivity, and internalizing emotions. In a sample of 1,211 justice-involved males (ages 15-22), quadratic growth models (i.e., intercepts, linear slopes, and quadratic slopes) of each type of aggression were regressed onto quadratic growth models of the covariates while controlling for the other type of aggression. After accounting for the level of reactive aggression, the level of proactive aggression was predicted by the level of CU traits. However, change in proactive aggression over time was not related to the change in any covariates. After accounting for proactive aggression, reactive aggression was predicted by impulsivity, both at the initial level and in change over time. Results support that proactive and reactive aggression are unique constructs with separate developmental trajectories and distinct covariates.

The development of youth antisocial behavior across time and context: A systematic review and integration of person-centered and variable-centered research.

Trajectories of youth antisocial behavior (ASB) are characterized by continuity and change. Although numerous longitudinal studies have examined ASB, findings from person-centered and variable-centered research have not yet been integrated. The present paper integrates findings across statistical methods for a more comprehensive understanding of the development of ASB. Neighborhood disadvantage is considered as a core moderator. The study protocol was registered in the PROSPERO database of systematic reviews (registration number CRD42021255820). The PsycINFO and PubMed databases were examined (September 2022) to identify longitudinal studies of youth aggression and/or rule-breaking. Results from person-centered and variable-centered studies were integrated via narrative synthesis, and a systematic quality assessment was conducted. Of 8227 studies identified, 136 met inclusion criteria. Our review indicated that rule-breaking trajectories were largely distinguished by differences in rate of change (i.e., slope), whereas aggression trajectories differed more by baseline level (i.e., intercept), particularly in childhood. For adolescents in disadvantaged neighborhoods, however, aggression trajectories differed by both intercept and slope. The respective importance of the intercept and slope differed across dimensions of ASB, developmental stage, and neighborhood residence. Neighborhood disadvantage was associated with trajectories of aggression, consistent with developmental theories emphasizing the role of person-environment interactions.

Uncovering heterogeneous cognitive trajectories in mild cognitive impairment: a data-driven approach

BackgroundGiven the complex and progressive nature of mild cognitive impairment (MCI), the ability to delineate and understand the heterogeneous cognitive trajectories is crucial for developing personalized medicine and informing trial design. The primary goals of this study were to examine whether different cognitive trajectories can be identified within subjects with MCI and, if present, to characterize each trajectory in relation to changes in all major Alzheimer’s disease (AD) biomarkers over time.MethodsIndividuals with a diagnosis of MCI at the first visit and ≥ 1 follow-up cognitive assessment were selected from the Alzheimer’s Disease Neuroimaging Initiative database (n = 936; age 73 ± 8; 40% female; 16 ± 3 years of education; 50% APOE4 carriers). Based on the Alzheimer’s Disease Assessment Scale-Cognitive Subscale-13 (ADAS-Cog-13) total scores from baseline up to 5 years follow-up, a non-parametric k-means longitudinal clustering method was performed to obtain clusters of individuals with similar patterns of cognitive decline. We further conducted a series of linear mixed-effects models to study the associations of cluster membership with longitudinal changes in other cognitive measures, neurodegeneration, and in vivo AD pathologies.ResultsFour distinct cognitive trajectories emerged. Cluster 1 consisted of 255 individuals (27%) with a nearly non-existent rate of change in the ADAS-Cog-13 over 5 years of follow-up and a healthy-looking biomarker profile. Individuals in the cluster 2 (n = 336, 35%) and 3 (n = 240, 26%) groups showed relatively mild and moderate cognitive decline trajectories, respectively. Cluster 4, comprising about 11% of our study sample (n = 105), exhibited an aggressive cognitive decline trajectory and was characterized by a pronouncedly abnormal biomarker profile.ConclusionsIndividuals with MCI show substantial heterogeneity in cognitive decline. Our findings may potentially contribute to improved trial design and patient stratification.

Speed-First: An Aggressive Gradient-Based Local Planner for Quadrotor Faster Flight

Autonomous flight for quadrotors is maturing with the development of real-time local trajectory planning. However, the current local planning method is too conservative to waste the agility of the quadrotors. So in this paper, we have focused on aggressive local trajectory planning and proposed a gradient-based planning method to rapidly plan faster executable trajectories while ensuring it is collision-free. A distance gradient information generation strategy is proposed, which finds a collision-free Hybrid-A* path to replace the control points in obstacles for safety and creates the distance gradient used in the back-end optimization. Besides, we present a novel and aggressive time span cost term to tackle unfeasibility and improve the overall trajectory speed. Extensive simulations and real-world experiments are tested to validate our method. The results show that our proposed method generates a more aggressive trajectory with a shorter planning time and a faster flight speed than the classical gradient-based method.

A Non-Optimization-Based Dynamic Path Planning for Autonomous Obstacle Avoidance

This article presents a non-optimization-based framework for path planning and tracking for evasive maneuvers in autonomous cars. The framework exploits a two-layer approach where a path planner generates a reference trajectory that is then tracked by a path-tracking controller. A nested curvature preview controller (CPC) implements path tracking. In this article, we show how to describe the closed-loop performance of the controller. The quantification of the closed-loop performance in the frequency domain guides the generation of the evasive path. In this way, the algorithm generates a path that avoids the obstacle (if possible) accounting for both static and dynamic constraints. The proposed framework, thus, provides a non-optimization-based way to integrate the characteristics of the path tracker in the path-planner algorithm, thus avoiding the need to define cost functions and use the third-party optimizers. This article validates the proposed evasive maneuver strategy in simulation and on an instrumented vehicle. First, we test the trajectory tracker, showing that it tracks aggressive trajectories (with a lateral acceleration close to 1 g) with an error smaller than 30 cm. Subsequently, we integrate the curvature preview with the path generator and show the joint generation-tracking performance in two different scenarios.

Co-developmental trajectories of aggression and rule-breaking from middle childhood to early adolescence: individual and environmental predictors.

This study examined the heterogeneous co-developmental trajectories of aggression and rule-breaking from middle childhood to early adolescence, as well as how these identified, distinct trajectories related to individual and environmental predictors. A total of 1944 Chinese elementary school students in grade 4 (45.5% girls, Mage = 10.06, SD = 0.57) completed measures on five occasions across two and a half years, using six-month intervals. Findings included: (a) Parallel process latent class growth modeling revealed four distinct co-developmental trajectory groups of aggression and rule-breaking: congruent-low (84.0%); moderate-decreasing aggression and high-decreasing rule-breaking (3.8%); moderate-increasing aggression (5.9%); and moderate-increasing rule-breaking (6.3%); (b) Multivariate logistic regression analyses revealed that children belonging to the high risk groups were more likely to experience multiple individual and environmental difficulties. Implications for prevention of aggression and rule-breaking were discussed.

Trajectories of physical and relational aggression across early childhood: Relations with peer risk factors.

The goal of the current study was to examine trajectories of relational and physical aggression in early childhood and evaluate peer predictors of these trajectories (i.e., peer rejection, relational victimization, and physical victimization). The study spanned three-time points (T1 in the spring, T2 in the fall, and T3 in the spring) in early childhood (N = 300; 44.0% girls; Mage = 44.70 months, SD = 4.38; 3.0% African American/Black, 7.6% Asian/Asian American/Pacific Islander, 1.0% Hispanic/Latinx, 11.3% multiracial, 62.1% White, and 15.0% missing/unknown). Observations of peer victimization and teacher report of peer rejection were collected at T1, and teacher report of aggression was collected at all time points. Results from piecewise latent growth models demonstrated that both forms of aggression decreased from T1 to T2 as children entered a new classroom and increased from T2 to T3 as they remained in that classroom. The increase in physical aggression from T2 to T3 was only significant for boys. Peer rejection at T1 emerged as a predictor of both intercepts and slopes from T1 to T2, and physical victimization predicted the physical aggression intercept and physical aggression slope from T1 to T2. Children high on these peer risk variables had higher initial levels of aggression, followed by a greater decrease in aggression from T1 to T2. Results underscore the importance of studying incremental change in aggression in early childhood and suggest that children who experience negative peer treatment have greater fluctuations in aggression over time.