A) Cliff avoidance task in adult conventional Syngap1 animals. We calculated the fraction of animals remaining on the platform over the course of a ten-minute testing period; chi square, X2(1)= 9.061, p<0.003. B) Modifications to cliff avoidance apparatus made for testing young mice. C) Risk-taking platform with quantifiable risk-taking postures in PND21 mice. D) Top-view heat map showing cumulative location of nose around the platform for each genotype. E) Quantification of risk-taking behaviors. left, number of edge departures during the test; t-test, p<0.001. right, cumulative fraction remaining on the apparatus as animals make their first full departure from the platform; chi square, X2(1)= 8.59, p<0.005.