A computer implemented method of adjusting natural language conversations between a user and a computer based on the user's cognitive state score while operating a vehicle, the method being implemented in the computer having one or more physical processors programmed with computer program instructions that, when executed by the one or more physical processors, cause the computer to perform the method, the method comprising: obtaining by the computer baseline physiological characteristics for the user from a database storing sensor information for baseline comparison, the baseline physiological characteristics determined from the sensor information of a user for baseline purposes; receiving, by the computer, a first utterance from the user during a conversation with the user; obtaining, by the computer, sensor information relating to at least a first physiological characteristic of the user; comparing, by the computer, the first physiological characteristic and the baseline physiological characteristics; determining, by the computer, a cognitive state score of the user based on the comparison of the first physiological characteristic and the baseline physiological characteristics; determining, by the computer, whether to disengage from the conversation with the user based on the cognitive state score of the user; and delaying, by the computer, a response to the first utterance responsive to a determination to disengage from the conversation with the user; obtaining, by the computer, second sensor information relating to at least a second physiological characteristic of the user; comparing, by the computer, the second physiological characteristic and the baseline physiological characteristics; determining, by the computer, a second cognitive state score of the user based on the comparison of the second physiological characteristic and the baseline physiological characteristics; determining, by the computer, that the conversation should be re-engaged with the user based on the second cognitive state score of the user; and re-engaging, by the computer, the conversation with the user, wherein re-engaging includes providing a response to the first utterance. obtaining by the computer baseline physiological characteristics for the user from a database storing sensor information for baseline comparison, the baseline physiological characteristics determined from the sensor information of a user for baseline purposes; receiving, by the computer, a first utterance from the user during a conversation with the user; obtaining, by the computer, sensor information relating to at least a first physiological characteristic of the user; comparing, by the computer, the first physiological characteristic and the baseline physiological characteristics; determining, by the computer, a cognitive state score of the user based on the comparison of the first physiological characteristic and the baseline physiological characteristics; determining, by the computer, whether to disengage from the conversation with the user based on the cognitive state score of the user; and delaying, by the computer, a response to the first utterance responsive to a determination to disengage from the conversation with the user; obtaining, by the computer, second sensor information relating to at least a second physiological characteristic of the user; comparing, by the computer, the second physiological characteristic and the baseline physiological characteristics; determining, by the computer, a second cognitive state score of the user based on the comparison of the second physiological characteristic and the baseline physiological characteristics; determining, by the computer, that the conversation should be re-engaged with the user based on the second cognitive state score of the user; and re-engaging, by the computer, the conversation with the user, wherein re-engaging includes providing a response to the first utterance.