從成本信念到學業成就：檢驗數學科家庭作業中分心與拖延的中介歷程

From Cost Beliefs to Academic Achievement: Examining the Mediating Roles of Homework Distraction and Procrastination in Mathematics

本研究以期望—價值理論為基礎，檢驗臺灣國中生在數學家庭作業中，成本信念（努力、機會、自我與情緒成本）對學業成就的影響機制，並進一步探討家庭作業中的非適應行為—分心與拖延—在此歷程所扮演的中介角色。本研究採用前瞻性縱貫設計，以臺灣國中七年級生為對象（N = 591），透過三個時段蒐集資料，並以結構方程模式進行分析。結果顯示：理論模式與觀察資料適配度良好。首先，不同成本對作業分心與作業拖延有不同預測效果：努力成本能降低作業分心與作業拖延，情緒成本則會增加兩者行為，機會成本僅對作業分心有促進效果，而自我成本則無任何顯著預測效果。其次，僅作業拖延能顯著負向預測學業成就。最後，努力成本可透過降低作業拖延、進而間接提升學業成就；而情緒成本則透過增加作業拖延、進而間接降低學業成就。本研究結果支持不同成本構面對非適應作業行為（分心與拖延）與學業表現具有差異性影響，而不同非適應行為對學業成就的預測效果亦不盡相同，僅作業拖延能顯著負向預測學業成就。整體而言，作業拖延扮演了成本信念與學業成就之間的重要中介角色，對未來相關研究與教學實踐具參考價值。

Homework, typically defined as learning tasks assigned by teachers to be completed outside regular class time (Cooper, 1989), is a central component of schooling worldwide and represents a widespread educational activity across cultures, ages, and ability levels (Warton, 2001). In Taiwan, lower-secondary students spend substantial amounts of time on homework, and mathematics homework in particular plays a key role in preparing for high-stakes examinations. Although homework is often assumed to promote practice, consolidation of knowledge, and the development of self-regulatory skills, students frequently experience attentional lapses, emotional strain, and motivational difficulties while working on homework (Trautwein & Köller, 2003; Xu & Wu, 2013). These challenges can give rise to maladaptive homework behaviors such as distraction and procrastination, which undermine the quality of homework engagement and have been linked to lower academic achievement and poorer psychological adjustment.
The contemporary expectancy-value theory (EVT) offers a foundational framework for explaining students’motivation and behavioral choices across learning contexts (Eccles et al., 1983; Wigfield & Eccles, 2000). According to EVT, students’engagement in academic tasks is shaped by their expectations for success and their subjective evaluations of task value, which together influence effort investment, persistence, and achievement-related choices (Eccles & Wigfield, 2002). In the homework context, these motivational beliefs play a central role in determining whether students approach homework with sustained effort or experience attentional difficulties, reduced motivation, and reliance on avoidance-oriented strategies (Trautwein et al., 2006).
Within EVT, task value is conceptualized as comprising not only intrinsic, attainment, and utility value but also the negative component of cost—a belief reflecting students’subjective evaluations of the effort, time, emotional strain, and opportunity sacrifices required to complete a task (Eccles & Wigfield, 2002; Perez et al., 2019; Sutter et al., 2024; Zhang & Jiang, 2025). EVT emphasizes that students weigh both benefits (positive values) and costs (negative values) when deciding whether to engage in an academic activity. When perceived cost becomes high, the overall subjective value of the task decreases, thereby reducing students’willingness to participate (Eccles et al., 1983). In the homework context, elevated perceived cost can impose considerable psychological burden, making students more susceptible to disengagement and various maladaptive patterns of homework behavior.
Drawing on this expectancy-value perspective, the present study focuses specifically on the role of perceived cost in the mathematics homework context, examining how effort, opportunity, ego, and emotional costs shape maladaptive homework behaviors (e.g., distraction and procrastination) and subsequent academic achievement. Although prior research has extensively examined expectancy and positive value components, the cost component has received comparatively limited empirical attention and is often treated as a secondary aspect of task value (Flake et al., 2015). This limited attention restricts a fuller understanding of cost as a negative motivational belief that may play a distinct role in explaining students’avoidance tendencies and homework-related difficulties (Jiang et al., 2018).
Recent studies have emphasized the importance of distinguishing cost from other value components, demonstrating that different types of cost uniquely predict avoidance tendencies, emotional strain, and maladaptive academic behaviors (e.g., Jiang et al., 2020; Jiang et al., 2018). Yet, empirical research remains limited, particularly within East Asian educational contexts where homework is culturally salient and academic competition is intensive. Moreover, although prior research has examined homework behaviors in relation to motivation or achievement, relatively few studies have investigated how the four cost dimensions are linked to specific maladaptive homework behaviors (e.g., distraction and procrastination) or how these behaviors subsequently shape academic achievement across time. The field still lacks longitudinal evidence clarifying whether distraction and procrastination serve as distinct mediators linking cost beliefs to academic outcomes or whether different types of cost play differentiated roles within the motivational process.
To address this research gap, the present study employed a prospective longitudinal design involving 591 seventh-grade students from northern, central, and southern Taiwan, with three waves of data collected from the second semester of Grade 7 through the second semester of Grade 8. Cost beliefs were assessed at Time 1 (T1; May 2023, second semester of Grade 7), homework distraction and procrastination at Time 2 (T2; November 2023, first semester of Grade 8), and academic achievement at Time 3(T3; May 2024, second semester of Grade 8). Data analysis was conducted using IBM SPSS Statistics 25 and LISREL 8.50. Structural equation modeling to evaluate the hypothesized model and the indirect pathways linking the constructs across time. This design allowed for a temporal ordering of variables, reduced common method bias, and provided a rigorous test of the proposed motivational process (Podsakoff et al., 2003).
The results indicated that the hypothesized model fits the observed data well, with all measurement indicators showing adequate psychometric properties. Building on this validated model, several patterns emerged from the structural paths. First, the four types of perceived cost showed differentiated predictive effects on homework distraction and procrastination. Effort cost negatively predicted both distraction and procrastination, whereas emotional cost positively predicted both behaviors. Opportunity cost positively predicted distraction but did not significantly predict procrastination, and ego cost did not significantly predict either behavior. Second, the two types of maladaptive homework behaviors exhibited different predictive effects on academic achievement. Homework procrastination significantly and negatively predicted academic achievement, whereas homework distraction did not show a significant effect on achievement. Finally, the indirect effects further clarified the motivational process: Effort cost indirectly enhanced academic achievement by reducing procrastination, whereas emotional cost indirectly undermined achievement by increasing procrastination. Overall, the findings highlight the heterogeneous impacts of cost dimensions on maladaptive homework behaviors (distraction and procrastination), as well as the differential effects of these behaviors on academic outcomes. They also emphasize the pivotal mediating role of homework procrastination between cost beliefs and academic achievement.
The implications of this study suggest that the differentiated roles of cost beliefs have practical significance for homework design and classroom support. Effort cost, which reduced procrastination and indirectly enhanced achievement, may reflect cultural norms that view persistence as a valued responsibility; thus, instructional practices that recognize students’sustained effort and provide formative feedback may enhance task commitment. Emotional cost, which increased procrastination and hindered achievement, points to the importance of creating homework environments that offer clearer structure, a greater sense of control, and guidance that helps students reappraise tasks to reduce anticipated stress. Finally, the positive link between opportunity cost and distraction highlights the need for strategies that help students manage competing after-school demands, such as clarifying the long-term value of assignments and supporting time-management routines.
Future research may further examine whether the culturally specific patterns identified in this study, particularly the adaptive function of effort cost among Taiwanese students, can be replicated in other cultural and educational contexts. The negative association between effort cost and homework procrastination, along with its indirect positive effect on achievement, differs from Western findings that typically regard cost as a negative motivational belief. This discrepancy may reflect the strong cultural emphasis on effort, responsibility, and moral obligation in Chinese societies. To clarify these culturally shaped motivational processes, additional replications with Chinese student samples and cross-cultural comparative studies are recommended. Moreover, although this study used a prospective longitudinal design, the absence of baseline academic achievement remains a limitation; incorporating prior achievement in future models would allow for a more rigorous test of the proposed indirect pathways. Finally, future research may also extend the model by integrating contextual factors highlighted in homework research, such as teacher autonomy support and features of homework design, to develop a more comprehensive understanding of homework processes.