It Is a Match! Timely Response to a Specific Target Boosts Concurrent Task Processing

Multitasking typically leads to interference. However, responding to attentionally demanding targets in a continuous task paradoxically enhances memory for concurrently presented images, known as the “attentional boost effect” (ABE). Previous research has attributed the ABE to a temporal orienting response induced by the release of norepinephrine from the locus coeruleus when a stimulus is classified as a target. In this study, we tested whether target classification and response decisions act in an all-or-none manner on the ABE, or whether the processes leading up to these decisions also modulate the ABE. Participants encoded objects into memory while monitoring a stream of letters and digits, pressing a key for target letters. To change the process leading to target classification, we asked participants to respond either to a specific target letter or an entire category of letters. To change the process leading to response, we asked participants to either respond immediately to the target or withhold the response until the appearance of the next stimulus. Despite successfully identifying the target and responding to it in all conditions, participants benefited less from target detection in category search than in exact search and less from delayed response than immediate response. These findings suggest that target and response decisions do not act in an all-or-none manner. Instead, the ABE and the temporal orienting response is sensitive to the speed of reaching a perceptual or response decision.