Neural correlates of a default response in a delayed go/no-go task

Working memory, the ability to temporarily retain task-relevant information across a delay, is frequently investigated using delayed matching-to-sample (DMTS) or delayed Go/No-Go tasks (DGNG). In DMTS tasks, sample cues instruct the animal which type of response has to be executed at the end of a delay. Typically, performance decreases with increasing delay duration, indicating that working memory fades across a delay. However, no such performance decrease has been found when the sample cues exist of present vs. absent stimuli, suggesting that pigeons do not rely on working memory, but seem to respond by default in those trials. We trained 3 pigeons in a DGNG task and found a similar default response pattern: The diverging slopes of the retention functions on correct Go and No-Go trials suggested that pigeons by default omitted their response following No-Go stimuli, but actively retained task-relevant information across the delay for successful responses on Go trials. We conducted single-cell recordings in the avian nidopallium caudolaterale, a structure comparable to the mammalian prefrontal cortex. On Go trials, many neurons displayed sustained elevated activity during the delay preceding the response, replicating previous findings and suggesting that task-relevant information was neurally represented and maintained across the delay. However, the same units did not show enhanced delay activity preceding correct response suppressions in No-Go trials. This activation-inactivation pattern presumably constitutes a neural correlate of the default response strategy observed in the DGNG task.     

When do irrelevant visual stimuli impair processing of identical targets?

Three experiments investigated whether the repeated-letter inferiority effect (RLIE) and repetition blindness (RB) are identical phenomena or not and how the RLIE can be reconciled with the flanker compatibility effect (FCE). Participants reported a masked target and ignored an unmasked distractor. We manipulated the type of distractor (identical, alternative target, or neutral), the order of presenting distractor and target, and the predictability of target location. When distractors preceded the targets, distractors identical to the target always caused deficits in target processing (i.e., RB). With simultaneous presentation, identical distractors caused deficits (i.e., an RLIE) for unpredictable target locations only. Yet the RLIE was significantly smaller than RB. This result suggests that simultaneously presented stimuli are identified serially, in random order, if target position is unpredictable. As a result, RB arises only in the 50% of all trials with identical distractors in which the distractor is identified before the target. With simultaneous presentation and predictable target location, however, parallel processing of targets and distractors was possible that gave rise to an FCE in recognition accuracy. Analyses of false alarm rates revealed no evidence of significant response biases.     

Action comprehension: deriving spatial and functional relations

A perceived action can be understood only when information about the action carried out and the objects used are taken into account. It was investigated how spatial and functional information contributes to establishing these relations. Participants observed static frames showing a hand wielding an instrument and a potential target object of the action. The 2 elements could either match or mismatch, spatially or functionally. Participants were required to judge only 1 of the 2 relations while ignoring the other. Both irrelevant spatial and functional mismatches affected judgments of the relevant relation. Moreover, the functional relation provided a context for the judgment of the spatial relation but not vice versa. The results are discussed in respect to recent accounts of action understanding.     

Detection of sound rise time by adults with dyslexia

Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia or compensated dyslexia and a control group performed a detection task with sound pairs of different rise times. Results showed that the participants with dyslexia differed from the control group in rise time detection and a correlation was found between rise time detection and reading and phonological skills. A subgroup of participants with lower sensitivity to rise time detection characterized by low accuracy in syllable-level phonological skills was found within the dyslexic group. Short stimuli containing only one rise time produced associations with phonological skills and reading, even in a language where the perception of rise time contrasts are not crucial for the signaling of phonemic contrast.     

The transition from synchronization to continuation tapping

The present study examined changes in timing at the transition from synchronization to continuation tapping and the role played by knowledge of the transition. Three experiments employed a pseudo-synchronization paradigm: At the transition, the pacing tones were replaced by identical feedback tones. In Experiment 1, participants were not informed when the transition would occur. Immediately following the transition, an acceleration of tapping was observed. In Experiment 2, participants were informed about the exact position of the transition, which was in addition marked by a pitch change. Nonetheless, the same acceleration occurred. Experiment 3 dissociated the actual from the expected position of the transition, without changing the results. In addition, the delay of the feedback tones was manipulated and was found to affect the rate of tapping in the continuation phase. A single delayed tone at the transition had no lasting effect, however. The results are interpreted in light of the synchronization-continuation model of Vorberg and Wing [Vorberg, D., & Wing, A. (1996). Modelling variability and dependence in timing. In H. Heuer, & S. W. Keele (Eds.), Handbook of perception and action, Vol. 2 (pp. 181-262). San Diego: Academic Press], with the added assumption that the synchronization tapping strategy is maintained in the continuation phase.     

A review of the H-reflex and M-wave in the human triceps surae

The soleus is the most commonly used muscle for H-reflex studies in humans, while limited comparable data have been produced from the gastrocnemii muscles. This article reviews the fundamental differences between the structure and function of the human soleus and gastrocnemii muscles, including recent data published about their complex innervation zones. Protocols for eliciting, recording, and assessing the H-reflex and M-wave magnitude in the human triceps surae are also discussed.     

Masculinity, Femininity, and the Bem Sex Role Inventory in Turkey

The aim of this study was to examine the masculinity and femininity scales of Bem Sex Role Inventory (BSRI) among Turkish university students. Five hundred thirty-six students (280 men and 256 women) volunteered to complete the short-form of the BSRI and answer demographic questions. In factor analyses, the original factor structure (Bem, 1981) was found both in the mens and womens data. Comparisons of the factor structures with target rotation (Procrustes rotation) and comparison indexes showed no difference between the factor structures found among men and women. The internal consistency of the masculinity and femininity scales was acceptable, and t-tests showed that women scored higher on the femininity scale, and men scored higher on the masculinity scale. There were significant differences between men and women only on two masculinity items, but significant differences were found in 8 (of 10) femininity items.     

Unique temporal change is the key to attentional capture

Abstract— Attentional capture refers to the observation that some events break through and attract one's attention even when one is engaged in a task for which these events are irrelevant. Previous research, focusing primarily on spatial factors, has shown that a new object is more salient in this regard than an abrupt change in an object's features. Here we show that feature changes can be as effective as new objects in capturing attention, provided that they occur during a period of temporal calm. Conversely, both feature changes and new objects are far less effective in capturing attention when they occur simultaneously with other display changes, such as coincident with the initial onset of the display or with small visual transients that occur during a display transition. These results highlight the importance of considering both space and time in studies of attentional capture; the most effective stimulus is unique in both dimensions.     

Determinants of stress-related growth: Gender,stressfulness of the event,and coping strategies

The present study aimed to investigate the determinants of stress-related growth. For this aim the associations of gender, stressfulness of the event, and three coping strategies (problem-oriented, fatalistic, and helplessness) with stress-related growth were tested by multiple regression analysis. Participants were 132 undergraduate students. Results revealed that females reported higher levels of stress-related growth than males, and as expected, higher levels of the stressfulness of the event associated with more stress-related growth. Furthermore, frequent utilization of problem-oriented and fatalistic coping strategies was associated with higher stress-related growth. These findings were discussed in the light of relevant literature and culture-specific features. This work has been supported by the Turkish Academy of Sciences, in the framework of the Young Scientist Award Program (TG-TUBA-GEB>P/2002-l-l 1).