A smart phone senses audio, imagery, and/or other stimulus from a user's environment, and acts autonomously to fulfill inferred or anticipated user desires. In one aspect, the detailed technology concerns phone-based cognition of a scene viewed by the phone's camera. In one detailed arrangement, image processing tasks applied to the scene are selected from among various alternatives by reference to resource costs, resource constraints, other stimulus information (e.g., audio), task substitutability, etc. The phone applies more or less resources to an image processing task depending on how successfully the task is proceeding, or based on the user's apparent interest in the task. In another detailed arrangement, data is referred to the cloud for analysis, or for gleaning. In still another detailed arrangement, cognition, and identification of appropriate device response(s), is aided by collateral information, such as context. A great number of other features and arrangements are also detailed.