Computer graphics in music performance research

Theories of skilled music performance must account for variations on what is written in traditional musical notation. Some variations are intentional and reflect structural features of the music that are chosen for emphasis by the performer. Current music notations are inadequate to reflect these variations. Computer applications are described that allow graphical and statistical examination of performance variations on traditional musical notation. An integrated set of visual and sound tools is provided that allows music to be recorded, edited, analyzed, and played back on electronic and acoustic musical instruments. The graphical format allows flexibility through the use of windows, compression, expansion, and scrolling of multiple sources of information, mapping of acoustic to visual dimensions, and scaling of different performance parameters without normalization. Experimental evidence from piano performances is used to demonstrate how graphical formats can aid research on human performance.     

Cocaine and crack users compared

Because crack use is such a recent phenomenon, little is known about users of this highly addictive drug, the harmful effects of which have been widely publicized. This study hypothesized that crack users would be more depressed and more alienated from family, friends, and school staff than would cocaine users, and would consider as less important reasons not to use crack and cocaine. The authors compared 411 users of cocaine (but not crack) to 156 crack users, all but 22 of whom had also used cocaine. The sample was derived from a larger random survey of 7th- through 12th-grade students in North Carolina. Results indicated that crack users were younger than cocaine users, made poorer grades, were more depressed, and were more likely to be alienated from family and friends. However, cocaine and crack users were equally unlikely to confide in anyone in their school if they had a drinking or drug problem. Further, crack users were more likely to have talked once to a teacher or counselor in the past year about their problems. The implications of these seemingly inconsistent findings are explored. Crack users appear to be a particularly vulnerable population.     

Assessing automaticity

We propose two principles that should be followed in the study of automaticity for cognitive processes. Both follow from the general rule that experimental research should be guided by a model of the task in question, frequently a process model. The first is that the concept of automaticity is best applied to component processes of complex behaviors rather than to behaviors as a whole. The second is that the criteria chosen for the identification of automaticity should be motivated by the processes in question. Examples are discussed of research programs that are relevant to each principle.     

Time course of free-choice priming effects explained by a simple accumulator model

Unconscious visual stimuli can be processed by human observers and modulate their behavior. This has been shown for masked prime stimuli that influence motor responses to subsequent target stimuli. Beyond this, masked stimuli can also affect participants' behavior when they are free to choose one of two response alternatives. This finding demonstrates that an apparently free-choice between alternative behaviors can be subject to influences that are outside of awareness. We report three experiments which exhibit that the temporal dynamic of free-choice priming effects corresponds to that of forced-choice priming effects. Forced-choice priming effects were relatively robust against variations of prime stimuli but sensitive to physical features of target stimuli. Free-choice priming effects, in contrast, depended largely on the stimulus-response compatibility of the prime. A simple accumulator model which accounts for forced-choice response priming can also explain free-choice priming effects by the assumption that unconscious stimuli can initiate motor responses when participants are engaged in a speeded choice-reaction time task. According to our analyses free-choice priming results from a response selection mechanism which integrates conscious and unconscious information from external, stimulus driven sources and also from internal sources.     

Aesthetic issues in spatial composition: effects of vertical position and perspective on framing single objects

Aesthetic preference for the vertical composition of single-object pictures was studied through a series of two-alternative forced-choice experiments. The results reveal the influence of several factors, including spatial asymmetries in the functional properties of the object and the typical position of the object relative to the observer. With asymmetric side views of objects, people generally prefer objects typically located below the observer's viewpoint (e.g., a bowl or swimming stingray) to be below the center of the frame and objects typically located above the observer's viewpoint (e.g., a light fixture or flying eagle) to be above the center of the frame. In addition, people generally prefer symmetric views of those same objects from directly above or directly below to be closer to the center of the frame. We suggest that these results can be unified by the hypothesis that people prefer the object's "affordance space" to be centered within the frame.