We report a new phenomenon in cross-modal cuing of visual spatial attention. Simultaneous auditory peripheral cues are “hyper-effective” - more effective than auditory peripheral cues that preceded the target stimulus with ample time for preparatory orienting. Observers were cued at several alerting times (cue-target onset asynchronies, CTOAs) to identify the orientation of one of four briefly presented Gabor stimuli, which were embedded in varied amounts of external noise (1). For visual central cues (VC), pre-cuing improved performance only in high external noise conditions, with performance monotonically improving with increased orienting intervals. For visual peripheral cues (VP), longer pre-cuing intervals improved performance, in this case in both the presence and absence of external noise. Surprisingly, for auditory peripheral cross-modal cues (AP), the performance for simultaneous cues exceeded even that for pre-cues with the largest orienting interval (CTOA = 240 ms). Although possibly related to reported perceptual advantages for simultaneous auditory and visual stimuli (2,3), to our knowledge, the “hyper effectiveness” of simultaneous auditory peripheral cues for visual processing is novel and may have major practical implications. The combined results suggest two separate processes: an orienting or alerting process that increases its effectiveness with additional lead time to the target with identical temporal dynamics but different magnitudes for the three cue types, and a cross-model marking process that provides privileged access to simultaneous targets based on cross-modal interaction. As in earlier reports (4, 5), visual central pre-cuing was associated with pure external noise exclusion, while peripheral auditory or visual pre-cuing yielded a mixture of stimulus enhancement and external noise exclusion. 1. Lu & Dosher, VR’98. 2. Stein et al, J Cog Neurosci’96. 3. Vroomen & Gelder, JEPHPP’00. 4. Dosher & Lu, Psyc Sci’00. 5. Lu & Dosher, JEPHPP’00.