A new Science Advances study links extra in-person visits to lower levels of misconduct in California prisons. The researchers found the clearest declines in use-of-force events and personal battery, with the effects concentrated shortly after visits.
How researchers separated visits from other factors
People who receive prison visits can differ from those who do not in ways that also affect behavior, which makes a simple comparison hard to interpret. The researchers tried to isolate the effect of visitation by using monthly gasoline-price changes as a source of outside variation in travel costs.
The analysis combined anonymized smartphone location data, California Department of Corrections and Rehabilitation misconduct records, and statewide fuel prices. It covered 35 state prisons from February 2017 through March 2020, producing 1,225 prison-month observations. Devices counted as visits only when they appeared inside prison boundaries during official weekend visiting hours, and the measure was adjusted for changes in smartphone coverage.
In the study’s preferred model, a 10% increase in visits was linked to a 2.04% decline in misconduct incidents per 100 incarcerated people. Looking only at extra visits associated with unexpected drops in gas prices, the estimated decline was about 1.7% for the same increase in visitation. A separate check using the state’s regular-visit records also found that higher gas prices sharply reduced visits.
What the gas-price method can and cannot show
Gas prices help address a persistent problem in prison-visitation research: Families with more resources or stronger relationships may be more likely to visit, while those same advantages could influence misconduct independently. Short-term fuel-price changes offer a way to study visits that become more or less likely because the trip suddenly costs more or less.
That design also narrows the finding. The estimate applies to visits that respond to gas prices, not every visit in every prison. The paper says those cost-sensitive visitors disproportionately came from lower-income, less-educated and more racially minoritized neighborhoods, making travel expenses a meaningful barrier.
The researchers could not identify whether a visitor was a parent, partner, child, friend or another relative, nor could they measure the quality of those relationships. Their misconduct data were aggregated at the prison level, so the study could not compare effects across individual demographic groups or incarceration histories. The results also do not address video visits.
The authors argue that reducing financial and logistical barriers to in-person visitation could be a cost-effective way to improve prison safety. They caution that the result comes from a specific group in California and may not carry over to other prison systems or to visits unaffected by travel costs.