In the 30 years since the 1994 Salamanca Statement, the concept of inclusive education has become global in scale, with the signatory countries implementing numerous educational policy measures to support the promotion of inclusive school practices. One important criterion of inclusive education, alongside the acquisition of academic knowledge, is ensuring the social participation of students with disabilities. A fundamental prerequisite for this is that they have quality peer relationships (Avramidis et al., 2018; Hassani et al., 2022). The possibility of establishing relationships between students with disabilities and their majority peers is largely determined by the attitudes that majority students have toward their peers with disabilities (Bossaert et al., 2011).

Negative attitudes of typically developing peers in mainstream schools can hinder inclusive education, much like physical barriers. They may lead to peer rejection, exclusion, bullying (de Boer et al., 2012), and social insecurity, impacting academic progress and increasing dropout risk (Jackson & Bracken, 1998). Additionally, they can contribute to mental health issues, including depression (Lund et al., 2009). Given the potential consequences of negative attitudes, it is important and relevant to examine the attitudes of mainstream students toward their peers with disabilities. Additionally, understanding how various independent variables—such as gender, age, and relationships with individuals with disabilities—affect these attitudes is crucial. Understanding these factors can aid in comprehending mainstream students' behaviors and reactions toward their peers with disabilities, as well as in designing, customizing, and ensuring the effectiveness of attitude-changing interventions.

The literature includes numerous studies measuring mainstream students' attitudes toward their peers with disabilities, using various measurement tools ( One of the most commonly used attitude scales for measuring students' attitudes toward their peers with disabilities is the Chedoke-McMaster Attitudes towards Children with Handicaps Scale (Armstrong et al., 2017; Sood et al., 2020), which was developed by Rosenbaum and colleagues in 1986. The attitude values are not comparable due to the use of different measurement tools, but research results indicate that there is no uniform consensus on the impact of independent variables (age, gender, communication, and friendship) on students' attitudes either (Freer, 2021). The aim of our study, is to contribute to the understanding of mainstream students' attitudes toward their peers with disabilities through a meta-analysis of results measured by the CATCH attitude scale. In our research, we will explore whether there has been any change in mainstream students' attitudes toward their peers with disabilities since 1986. Additionally, the analysis aims to provide a clearer picture of possible geographical differences, as well as the impact of variables such as age, gender, relationships with peers with disabilities, and having a family member with a disability on attitudes. Understanding these factors will help in organizing more effective interventions aimed at supporting the inclusion of students with disabilities. We guided our research by the following questions.

1. Since the introduction of the Chedoke-McMaster Attitudes towards Children with Handicaps Scale (CATCH) in 1986, how has the attitude of majority students toward their peers with disabilities changed over time?
2. What does the geographical distribution of attitude scores measured by the scale reveal?
3. What correlations can be identified through the meta-analysis regarding the impact of age, gender, relationships with peers with disabilities, and having a family member with a disability on the attitudes of majority students towards their peers with disabilities?

As the first step of our research, we conducted a systematic literature review using PRISMA (Page et al. 2021) guidelines to provide an organized and transparent approach for gathering and evaluating the results of empirical studies of our research topic. We searched for the studies in six databases, supplementing the search with hand searches. We formulated our inclusion criteria for study selection based on the objectives of our systematic review, research questions, and relevant literature. Our review focused on studies published between 1986 and 2023 in international peer-reviewed journals, in either English or Hungarian, that used the CATCH attitude questionnaire to examine the attitudes of mainstream students aged who attend to primary or secondary education toward their peers with disabilities. We did not include studies in our analysis that used a different questionnaire to measure students' attitudes, nor did we include studies that did not examine the primary or secondary school population. During the data extraction process, we collected information on the publication year, research location, as well as sample size, mean, and standard deviation for the entire population, covering both global attitude scores and the scores of the different attitude components. For the meta-analysis, we also required sample size, mean, and standard deviation related to the independent variables (age, gender, peers with disabilities, family member with a disability). We conducted descriptive statistical analysis on the data and, and in relation to our research questions, we performed regression analysis weighted by sample sizes, t-tests weighted by sample sizes, and meta-analysis. In a meta-analysis, we examined the overall effect of gender, peer relationship with a student with a disability and the presence of a family member with a disability in the student's life on the student's attitudes towards their peers with disabilities. Since some of the studies had a small sample sizes, the standardized mean difference formula (Hedges g-estimation) was used to calculate the effect size of each study to measure the difference in attitudes between the different groups, as it corrects for the small sample bias. We calculated the average effect size and the 95% confidence interval using the random effects model. We determined the effect sizes based on Cohen's (1988) interpretation, which categorizes values around 0.80 and above as large, values around 0.50 as medium, and values below 0.20 as small. We assessed the heterogeneity of effect sizes using the Q statistic and I² estimate.

The results show that the average attitude score of the students in the examined sample (N=18,722) has changed in a negative direction over the past 38 years. Our results highlight that students' gender and the presence of a family member with a disability have a small impact, while having a peer with a disability has a moderate positive effect on students' attitudes toward their peers with disabilities. Our results align with studies that used a different attitude questionnaire for their investigation (Barr and Bracchitta, 2012). The gender differences may be driven by educational and cultural influences, but the results may also reflect the impact of developmental differences between girls and boys (Dias et al., 2020). A meta-analysis of the impact of having a family member or peer with a disability on attitudes revealed that having a family member has a small effect, while peer relationships have a moderate effect on students' attitudes toward their peers with disabilities. In the current educational policy context supporting inclusion, our results can provide valuable information to educators in order to implement effective interventions for the widespread realization of inclusion. Our results indicate that educational interventions aimed at promoting positive attitudes should focus on knowledge-sharing about students with disabilities, so that majority students have access to as much relevant information as possible about their peers with disabilities. In addition, it would be important to create more situations in schools that support the interaction between majority students and their peers with disabilities, allowing them to get to know each other and engage in the process of making friends.

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