Does Timbre Modulate Visual Perception? Exploring Crossmodal Interactions

Musical timbre is often described using terms from non-auditory senses, mainly vision and touch; but it is not clear whether crossmodality in timbre semantics reflects multisensory processing or simply linguistic convention. If multisensory processing is involved in timbre perception, the mechanism governing the interaction remains unknown. To investigate whether timbres commonly perceived as “bright-dark” facilitate or interfere with visual perception (darkness-brightness), we designed two speeded classification experiments. Participants were presented consecutive images of slightly varying (or the same) brightness along with task-irrelevant auditory primes (“bright” or “dark” tones) and asked to quickly identify whether the second image was brighter/darker than the first. Incongruent prime-stimulus combinations produced significantly more response errors compared to congruent combinations but choice reaction time was unaffected. Furthermore, responses in a deceptive identical-image condition indicated subtle semantically congruent response bias. Additionally, in Experiment 2 (which also incorporated a spatial texture task), measures of reaction time (RT) and accuracy were used to construct speed-accuracy tradeoff functions (SATFs) in order to critically compare two hypothesized mechanisms for timbre-based crossmodal interactions, sensory response change vs. shift in response criterion. Results of the SATF analysis are largely consistent with the response criterion hypothesis, although without conclusively ruling out sensory change.

EXPRESS: Effects of a Neutral Warning Signal on Spatial Two-Choice Reactions

Posner et al. (1973) reported that, at short fixed foreperiods, a neutral warning tone reduced reaction times (RTs) in a visual two-choice task while increasing error rates for both spatially compatible and incompatible stimulus-response mappings. Consequently, they concluded that alertness induced by the warning does not affect the efficiency of information processing but the setting of a response criterion. We conducted two experiments to determine the conditions under which the tradeoff occurs. In Experiment 1, participants performed the same two-choice task as in Posner et al.’s study without RT feedback. Results showed that the warning tone speeded responses with no evidence of speed/accuracy tradeoff. In Experiment 2, RT feedback was provided after each response, and a speed/accuracy trade off was found for the 50-ms foreperiod. However, better information-processing efficiency was evident for the 200-ms foreperiod. We conclude that the foreperiod effect of a 50-ms foreperiod is a result of response-criterion adjustment and that providing trial-level RT feedback is critical for replicating this pattern. On the other hand, fixed foreperiods of 200-ms or longer benefit both speed and accuracy, implying a more controlled preparation component that improves response efficiency.

Why collaboration reduces suggestibility: The role of source-monitoring processes and retrieval strategies

Previous research found that collaboration reduces the tendency to yield to misleading questions. Here, the aim was to determine whether this occurs because collaboration induces a conservative change in response criterion or because it promotes more efficient error-checking strategies. To this purpose, we compared the performance of collaborative and nominal triads in the Gudjonsson Suggestibility Scale. Critically, we recorded conversations during retrieval, allowing us to compute inclusive scores and analyze retrieval strategies. Confirming previous evidence, results showed that collaborative groups yielded less to leading questions; however, the differences between collaborative and nominal groups in yield 1 were canceled when we took into account questions to which at least one participant in the collaborative group gave in but was corrected by collaborators during the discussion (the so-called inclusive scores). This was not the case for yield 2 and total suggestibility scores. Also, the analysis of retrieval strategies indicated that collaborative groups who used process-focused strategies (such as correction and cross-cueing) to a greater extent were less likely to change their responses after receiving the negative feedback and were less suggestible. We conclude that, while the use of error-checking and process-focused strategies played a role in reducing suggestibility in collaborative groups, the administration of negative feedback induced members of collaborative groups to adopt a more conservative response criterion. These results contribute to the understanding of the conditions that maximize the positive effects of collaborative retrieval. They have implications for policymakers and police practitioners, specifying when and how collaboration might be allowed.

Is This Within Reach? Left but Not Right Brain Damage Affects Affordance Judgment Tendencies

The ability to judge accurately whether or not an action can be accomplished successfully is critical for selecting appropriate response options that enable adaptive behaviors. Such affordance judgments are thought to rely on the perceived fit between environmental properties and knowledge of one's current physical capabilities. Little, however, is currently known about the ability of individuals to judge their own affordances following a stroke, or about the underlying neural mechanisms involved. To address these issues, we employed a signal detection approach to investigate the impact of left or right hemisphere injuries on judgments of whether a visual object was located within reach while remaining still (i.e., reachability). Regarding perceptual sensitivity and accuracy in judging reachability, there were no significant group differences between healthy controls (N = 29), right brain damaged (RBD, N = 17) and left brain damaged stroke patients (LBD, N = 17). However, while healthy controls and RBD patients demonstrated a negative response criterion and thus overestimated their reach capability, LBD patients' average response criterion converged to zero, indicating no judgment tendency. Critically, the LBD group's judgment tendency pattern is consistent with previous findings in this same sample on an affordance judgment task that required estimating whether the hand can fit through apertures (Randerath et al., 2018). Lesion analysis suggests that this loss of judgment tendency may be associated with damage to the left insula, the left parietal and middle temporal lobe. Based on these results, we propose that damage to the left ventro-dorsal stream disrupts the retrieval and processing of a stable criterion, leading to stronger reliance on intact on-line body-perceptive processes computed within the preserved bilateral dorsal network.