A schematic illustration of the proposed clear distinction between demanded effort (associated with task properties) and the two less easily distinguished (hence fuzzily bounded) behaviorally or physiologically measurable properties of exerted and (self‐)assessed effort. Demanded effort is quantifiable in terms of task properties such as SNR, number of competing talkers, memory load, degree of distortion of target speech, and so forth. Exerted and assessed effort are typically quantified using the behavioral and physiological measures discussed in the text. We also indicate a proposed distinction between externally and internally directed cognitive resources and associated these both mainly with exerted effort because, while they are often distinguished theoretically (see text), they may or may not be distinguishable in terms of how listeners feel about (assess) the effort they are exerting. SNR, signal‐to‐noise ratios.

Methods of assessing capacities for cumulative culture. Top: solution success increases in a chain of multiple individuals attempting a single problem. Below: solution success increases with demonstration success in single individuals attempting multiple problems.