Figure 1.

Summary of the protocol. (a) Parent & Stranger: Direct fear learning protocol. On Day 1, parents were exposed to a direct fear conditioning protocol where two colored lamps were presented, one was paired with a shock 5 times out of 8 presentations (CS + Parent; red or blue) while the other was never paired with a shock (CS −; yellow). A stranger adult was exposed to a similar procedure except that a different color (e.g., red) was used for the CS + . The same color that was used for the CS − of the parent was used for the stranger (yellow, CS −). Both the stranger and the adult were filmed during this procedure. Note that the stranger video was matched to the sex of the participating parent. All children participating with their mother saw the same stranger video (stranger woman) and all children participating with their father saw the same stranger video (stranger men). (b) Child – Observational learning stage. The child was presented with both videos (observational fear learning phase). After that, the shock electrodes were attached to the child’s hand and he/she was instructed that shocks could be delivered (no shock was delivered to the child). The child was directly exposed to all three colored lights (CS + Parent, CS + Stranger, and CS −) (direct expression test and extinction learning). On Day 2, the child was once again presented with all three stimuli (CS + Parent, CS + Stranger, and CS −) and no shock was delivered (direct retention test).