Purpose: Neurologically normal observers misperceive the midpoint of horizontal lines as systematically leftward of veridical center, a phenomenon known as pseudoneglect (PN). However, a rightward bias characterizes the perceived midpoint (PSE) of horizontal spatial intervals defined auditorily. Lateral visual cues significantly bias PSE. Using a tachistoscopic visual line bisection (LB) paradigm we assess: 1) whether exogenous lateral auditory cues can bias PSE; and 2) the manner in which auditory (A) and visual (V) cues combine to jointly influence PSE. Methods: Forty-six dextral subjects completed a tachistoscopic LB task. In addition to a no-cue condition, subjects made LB judgments where V and A cues were delivered as unisensory stimuli, and in multisensory combinations, to the right (R) and left (L) line endpoints. Conditions were randomly interleaved. Multisensory cue combinations were spatially congruent (VRAR, VLAL) or discordant (VLAR, VRAL). Results: Table 1 reports mean PSE in degrees visual angle relative to veridical line midpoint for all conditions. There was a significant tonic leftward bias in PSE (PN). Lateral cues influenced PSE such that L cues induced greater leftward bias than R cues. Leftward bias was significantly greater for V cues than for A cues overall. Leftward bias was strongest for VL cues and weakest for VR cues. Table 2 discloses the weights assigned to PSE values in the unisensory A (WA) and V (WV) conditions which optimally predicted PSE values obtained in the multisensory AV conditions. There is a significant hemifield asymmetry in the weights assigned to A and V cues, where VL cues are more heavily weighted than AL or AR cues, but VR cues are equally weighted with AL or AR cues. Conclusions: We confirm a tonic leftward bias in LB PSE. VL cues induce a large leftward shift in PSE and are significantly stronger than A cues, whereas VR cues are equipotent with A cues. These results are consistent with a prepotent vector of visuospatial attention to left hemispace, and a prepotent vector of audiospatial attention to right hemispace, and imply the existence of separate attentional networks for A and V stimuli. Since the weights for unisensory A and V cues were optimized by least-squares regression to fit PSEs in the AV conditions without constraint, it is especially noteworthy that their sums in each AV condition are nonsignificantly different from unity. This result is consistent with Bayesian cue combination. Bayesian combination implies that some response parameter to exogenous hemispatial A and V cues possesses variances which are inversely proportional to these empirically derived weights. This parameter is yet to be determined; a likely candidate is cue localizability.