Suggestiveness in photospread line-ups: Similarity induces distinctiveness

The present research examined whether line-ups based on target (‘suspect’) face similarity are biased or suggestive. Four experiments are described in which subjects constructed photographic line-ups by selecting foils similar in appearance to a target. Later, another group of subjects who had not seen the faces before (mock witnesses) were asked to pick out the targets from the line-ups. All four experiments showed that mock witnesses selected the target significantly more often than expected by chance, thereby demonstrating suggestiveness. Three alternative line-up construction methods were also evaluated. In these methods, foil selection was based not only on target similarity but also on similarity with one or more of the other line-up faces. Results showed that alternative line-up targets were not selected significantly more often than chance, suggesting that bias was reduced. An overall analysis showed that the alternative line-ups were significantly less suggestive than target-based line-ups. The results indicate that foil selection procedures that incorporate foil-to-foil similarity produce fairer line-ups than those exclusively based on target similarity.     

Diathesis-stress models of psychopathology: A quantitative genetic perspective

When genetics is considered in diathesis-stress models of psychopathology, it is often assumed that heredity provides the diathesis and environmental factors are responsible for the stressor. We discuss two quantitative genetic models relevant to the diathesis-stress construct. One model focuses on genotype-environment interaction, which is the usual way in which genetic influence is represented in diathesis-stress models. A second model—genotype-environment correlation—provides an alternative that represents both genetic and environmental influences relevant to the development of psychopathology. Implications of these models for clinical research are discussed.     

Convergent methods in psychomusical research based on integrated,interactive computer control

Much of what we learn from an experiment depends on what we ask of the subjects and how we ask it. Most music perception and cognition research is implemented using a single methodology. Recently, questions have been raised about the validity and generalizability of such a limited approach, particularly regarding such complicated theoretical constructs as musical tonality. We propose that a useful technique is to converge on the answer to experimental questions by applying multiple methods, in essence, simultaneously investigating the central research question as well as ancillary questions of method. Such an approach is facilitated by a computer hardware and software system that integrates experimental design, data collection, data analysis, and data dissemination, linking off-the-shelf components through standard file formats and data-exchange protocols. The list-based system, using an IBM-type PC running Windows 3.0, handles real-time natural sound sampling and playback, signal synthesis and analysis, MIDI input and output, digitized picture display, and various subject-response mechanisms. On the basis of graphical icons, the integrated system can be used to build custom experimental designs. Examples of convergent psychomusical experiments that were designed, implemented, and analyzed using the system are discussed.     

Increasing the intelligibility of speech through multiple phonemic restorations

Outside of the laboratory, listening conditions are often less than ideal, and when attending to sounds from a particular source, portions are often obliterated by extraneous noises. However, listeners possess rather elegant reconstructive mechanisms. Restoration can be complete, so that missing segments are indistinguishable from those actually present and the listener is unaware that the signal is fragmented. This phenomenon, called temporal induction (TI), has been studied extensively with nonverbal signals and to a lesser extent with speech. Earlier studies have demonstrated that TI can produce illusory continuity spanning gaps of a few hundred milliseconds when portions of a signal are replaced by a louder sound capable of masking the signal were it actually present. The present study employed various types of speech signals with periodic gaps and measured the effects upon intelligibility produced by filling these gaps with noises. Enhancement of intelligibility through multiple phonemic restoration occurred when the acoustic requirements for TI were met and when sufficient contextual information was available in the remaining speech fragments. It appears that phonemic restoration is a specialized form of TI that uses linguistic skills for the reconstruction of obliterated speech.