Against a backdrop of widening income inequality and growing disparities in parental spending on children, the gap in academic readiness between kindergartners from high- and low-income families has surprisingly declined, according to new research.

A study published in AERA Open, a journal of the American Educational Research Association, found that the gap in preparedness for school had decreased by 10 percent in math and 16 percent in reading between 1998 and 2010 at a time when all new kindergartners are arriving better prepared than prior generations.

The new finding documents a reversal in a long-term trend between the 1970s and the 1990s when the academic readiness gap between low- and higher-income children of kindergarten age grew by about 40 percent.

The new study also found that the white-Hispanic gap in kindergarten readiness narrowed by about 14 percent between 1998 and 2010. The white-black readiness gap appeared to have narrowed as well over the same period, but the margin of error was too wide for the study to conclude so with certainty.

Researchers Sean F. Reardon of Stanford University and Ximena A. Portilla of the research firm MDRC analyzed nationally representative data from the National Center for Education Statistics to compare the reading, writing and math readiness skills of roughly 17,000 incoming kindergarten students in 2010 to those of about 20,000 students who entered school 12 years earlier. To measure academic preparedness by household income, they compared students from the poorest 10 percent of families with students from the wealthiest 10 percent.

The authors attribute the closing readiness gap to a variety of factors, including increasing availability of quality preschool programs and children’s access to better health care.

Despite the positive developments cited in the study, the kindergarten readiness gaps by both race and income remain large. The researchers noted that at the rate the gaps have declined in the 12 years studied, it would take another 60 to 110 years for them to be eliminated.