Small talk

It’s a small world. But according to diffusion theory, communication between small groups can have far-reaching effects, accelerating the spread and adoption of new ideas. One example of ‘small-group strategy’ successfully influencing behaviour change is the ‘Stop AIDS Project’ of the mid-1980s. The program, which became a template for HIV prevention interventions, shows how an understanding of diffusion theory can help save lives.

The Stop AIDS Project (SAP) was founded in 1985 to prevent HIV transmission in San Francisco following a rise in deaths from AIDS. The program, designed by and for gay men, relied on community-based organising to drive behaviour change. SAP recruited outreach workers – who were gay and often HIV-positive – to organise small group meetings of ten to twelve men in various San Francisco neighbourhoods where gay men lived. The meetings focused on educating participants about HIV transmission and safe sex practices. Each session concluded with participants being asked if they planned to practice safer sex, with willing individuals invited to organise and lead future small-group meetings.

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“Communication between small groups can have far-reaching effects, accelerating the spread and adoption of new ideas.”

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Architects of the program believed that if they could reach a critical mass of opinion leaders within San Francisco’s gay community, HIV prevention practices would spread across the community through interpersonal networks. Within 2 years, SAP had trained 7,000 individuals through small-group meetings, and these, in turn,  reached a further 30,000 of San Francisco’s 142,000-strong gay population. However, by 1987, attendances declined leading to the program’s closure.

Despite this, the intervention correlated with a huge improvement in HIV trends. HIV transmission rates in San Francisco fell to just 1%, while the rate of unprotected intercourse – a big driver of HIV transmission in San Francisco – plummeted. As a result, AIDS-related deaths decreased significantly.

Whilst these outcomes cannot solely be attributed to the Stop AIDS effort, SAP’s small-group strategy played an important part in slowing down the spread of the epidemic in San Francisco. The community-based model has since inspired similar grassroots prevention programs across the world. Their successes underline the power of interpersonal networks in the spread and adoption of new ideas.