But most often the response was either nothing at all, or a surprised stare because I had spoken. (Para. 6)
Meaning: But in most cases people didn't say anything in return, or they simply stared at me, feeling surprised at my greeting.
response: n. a reply; an action done in answer
It seems that the child has some difficulties in making responses. 看来这个小孩在作反应方面有困难。
The study of behavior of every kind is a study of responses to situations and events. 对各种行为的研究实际上是对各种环境和事件反应能力的研究。