Naturalistic evaluation of suicidal ideation: variability and relation to attempt status

Suicidal ideation has been thought to have a relatively stable course across weeks and months. However, daily changes in levels of ideation have not been adequately examined despite the importance of potential variability clinically and conceptually. For example, it has been suggested that variability in suicidal ideation may become less closely tied to variability in other mood symptoms (e.g., depression, hopelessness) among individuals with multiple suicide attempts. The present report had two related goals: (1) to prospectively evaluate suicidal ideation and related mood symptoms, and (2) to determine whether suicide attempt status predicted a decreased association between ideation and other mood symptoms. Non-clinical participants (N=108) with varying levels of suicidal ideation and number of previous suicide attempts completed the beck hopelessness scale (BHS), beck depression inventory (BDI), and suicide probability scale (SPS) every day for 4 weeks. Findings suggested considerable variability in suicidal ideation, especially for multiple attempters. Multiple attempt status predicted a decreased association between suicidal ideation and depression, although the results were only marginally significant. These findings have implications for conceptual models of suicide risk as well as assessment and treatment of suicidal individuals.     

Detection of acoustic repetition for very long stochastic patterns

Guttman and Julesz (1963) employed recycling frozen noise segments (RFNs) as model stimuli in their classic study of the lower limits for periodicity detection and short-term auditory memory. They reported that listeners can hear iteration of these stochastic signals effortlessly as "motorboating" for repetition periods ranging from 50 to 250 msec and as "whooshing" from 250 msec to 1 sec. Both motorboating and whooshing RFNs are global percepts encompassing the entire period, as are RFNs in the pitch range (repetition periods shorter than 50 msec). However, with continued listening to whooshing (but not motorboating) RFNs, individuals hear recurrent brief components such as clanks and thumps that are characteristic of the particular waveform. Experiment 1 of the present study describes a cross-modal cuing procedure that enables listeners to store and then recognize the recurrence of portions of frozen noise waveforms that are repeated after intervals of 10 sec or more. Experiment 2 compares the relative saliencies of different spectral regions in enabling listeners to detect repetition of these long-period patterns. Special difficulty was encountered with the 6-kHz band of RFNs, possibly due to the lack of fine-structure phase locking at this frequency range. In addition, a similarity is noted between the organizational principles operating over particular durational ranges of stochastic patterns and the characteristics of traditional hierarchical units of speech having corresponding durations.     

Learning fine-grained and category information in navigable real-world space

Spatial judgments are affected by both fine-grained and categorical knowledge. We investigated whether, and how, the two forms of knowledge are learned in real-world, navigable space, as well as the time course of learning each type of knowledge. Participants were Northwestern University undergraduates who estimated the locations of buildings and other landmarks on campus. The Northwestern campus is roughly divided into three regions whose borders are not easy to discern, either from a map or by navigation. Nevertheless, students often refer to these regions linguistically and use them when making housing decisions, choosing classes, and so forth. We found that knowledge of both the fine-grained configuration of locations and the regional distinctions increased with time. However, regional influences on judgments occurred later in students’ time on campus. Consequently, computed distances across the nonexistent border between north and south campus locations became more biased with time. The results have implications for understanding how spatial representations develop in navigable environments.     

The role of the dorsal CA1 and ventral CA1 in memory for the temporal order of a sequence of odors

Memory for the temporal order of a sequence of odors was assessed in male rats. A sequence of five odors mixed in sand was presented in digging cups one at a time to each rat in a sequence that varied on each trial. A reward was buried in each cup. Following the fifth odor, two of the previous five odors were presented simultaneously and the rat needed to choose the odor that occurred earliest in the sequence to receive a reward. Temporal separations of 1, 2, or 3 were used which represented the number of odors that occurred between the two odors in the sequence. Once pre-operative criterion was reached, rats received a control, dorsal CA1 (dCA1), or ventral CA1 (vCA1) lesion and were retested on the task. On post-operative trials, only the vCA1 group was impaired relative to both control and dCA1 groups. All groups of rats could discriminate between the odors. The data suggest that the vCA1, but not dorsal CA1, is involved in separating sensory events (odors) in time so that one odor can be remembered separate from another odor.     

An Evaluation of a Brief Multiple-Stimulus Without Replacement Preference Assessment Conducted in an Electronic Pictorial Format

We compared the results of a brief electronic pictorial multiple-stimulus without replacement (EP-MSWO) preference assessment to a brief tangible MSWO preference assessment in five children with autism. Results of both assessments yielded a match between high preferred (HP) toys for four participants and low preferred toys for three participants. The overall correlation between assessments across participants was strong and statistically significant (ρ = .67, p < .01). A reinforcer assessment conducted with three participants confirmed HP toys identified in the EP-MSWO functioned as reinforcers.     

Auditory temporal discrimination by trained listeners

Previous reports from this laboratory have shown that untrained listeners cannot name the order of sounds in extended sequences of unrelated items such as hisses, tones, and buzzes at item durations of 200 msec, even though identification of order for the sounds of speech and music is accomplished readily at much shorter item durations. The present study indicates that under appropriate conditions subjects can be trained to distinguish between and to identify permuted orders within sequences of nonrelated sounds each lasting only 10 msec or less. Evidence is presented suggesting that much of what passes for direct identification of order is actually based on prior identification of a larger pattern. Two principal mechanisms seem to mediate discrimination of auditory temporal order: (1) fine resolution (requiring prior training) permitting identification of over-all patterns and capable of operating with item durations of only a few msec; (2) coarse resolution (special prior training not required) allowing naming of order of items having minimal durations usually above 200 msec for unfamiliar sequences.     

Visual control of step length during running over irregular terrain

Running over uneven ground requires visually regulating step length to secure proper footing. To examine how this is achieved, we studied subjects running on a treadmill on a series of irregularly spaced targets. The movements of their lower limbs and coccyx relative to the targets were monitored opto-electronically by a Selspot system. The results indicated that step length was adjusted to strike the targets primarily by varying the vertical component of impulse applied to the ground during the stance phase. In contrast, horizontal impulse was not varied significantly, and changing the reach forward of the foot on landing contributed little to variation in step length. Changing the vertical impulse simply altered the step time proportionately. Thus the data are consistent with a time-based model in which vertical impulse is modulated by the optic variable delta tau (Lee, 1976) specifying the time gap that has to be bridged by the runner between two targets.