The role of effort in an SDT paradigm has not been adequately investigated using only natural contingencies, where hits are the only reinforced responses. Fixed-ratio (FR) requirement as a measure of effort was systematically varied in a go/no-go signal detection task. Hens were trained to discriminate between a brighter keylight (S+) and a dimmer keylight (S-), where a fixed-ratio response requirement was in effect on S+ trials (i.e., for a “go” response) and a secondary, ‘advance’ key progressed to the next trial at any point following an observation response (i.e., a “no-go” response). A negative, linear relationship was discovered between FR requirement and hit rate. Although FR requirement variation was not found to significantly influence specificity performance, a graphical trend was observed such that, as FR increased, specificity generally increased before levelling off at a FR 16 response requirement. Comparisons between original and reinstated conditions suggest that performance was not affected by an order or practice effect. Implications and limitations of these findings are discussed, and considerations for future research are identified, such as generalisation of these findings across species and differing types of ‘effort’.