The relevance of temporal cues in a fish sound: a first experimental investigation using modified signals in cichlids

Playback experiments have been a useful tool for studying the function of sounds and the relevance of different sound characteristics in signal recognition in many different species of vertebrates. However, successful playback experiments in sound-producing fish remain rare, and few studies have investigated the role of particular sound features in the encoding of information. In this study, we set-up an apparatus in order to test the relevance of acoustic signals in males of the cichlid Metriaclima zebra. We found that territorial males responded more to playbacks by increasing their territorial activity and approaching the loudspeaker during and after playbacks. If sounds are used to indicate the presence of a competitor, we modified two sound characteristics, that is, the pulse period and the number of pulses, in order to investigate whether the observed behavioural response was modulated by the temporal structure of sounds recorded during aggressive interactions. Modified sounds yielded little or no effect on the behavioural response they elicited in territorial males, suggesting a high tolerance for variations in pulse period and number of pulses. The biological function of sounds in M. zebra and the lack of responsiveness to our temporal modifications are discussed.     

Functional cerebral changes in multiple sclerosis patients during an autobiographical memory test

Our aim was to investigate the functional underpinnings of autobiographical memory (AM) impairment in multiple sclerosis (MS) patients. To that end, 18 patients and 18 controls underwent the autobiographical interview (AI). Subsequently, the 36 participants underwent a functional magnetic resonance imaging (fMRI) session designed to assess the construction and elaboration of AMs. A categorical control task was also presented. Patients were trained in the fMRI procedure to optimise the procedural aspects accompanying the task itself. Although the patients obtained significantly poorer AI scores (p < .001), their performance on the easier AM fMRI task was efficiently carried out, allowing relevant comparisons with healthy controls. Relatively to healthy controls, the patients showed increased and bilateral cerebral activations (p < .005) during the construction and elaboration phases. The prefrontal, temporal and posterior cerebral region activations were located within the core network sustaining AM, with the bilateral prefrontal region being centrally involved. The parametric neural responses to the difficulty of access and amount of details of memories were also significantly different for the two groups, with the right hippocampal region showing a particularly increased recruitment (p < .005). The findings suggested the presence of functional cerebral changes during AM performance and supported the presence of AM retrieval deficit in MS patients.     

The effects of emotional content on source monitoring in fibromyalgia patients

Source confusion refers to a person’s failure to distinguish whether an event has been actually seen or simply imagined. Nevertheless, prior research has demonstrated a reduction of source confusion for negative arousing information. According to the emotional-congruence effect, this emotional benefit is likely observed in patients suffering from chronic pain. This hypothesis was tested on 15 patients suffering of fibromyalgia syndrome (FMS) and 15 healthy women. In a source-monitoring task, participants had to decide whether positive, negative, and neutral words were imagined or seen with a picture. The results showed recognition deficits and more source confusion for FMS patients compared to controls. Contrary to the hypothesis of negativity bias in fibromyalgia, patients exhibited enhanced recognition for both positive and negative words. Moreover, they showed better source memory for the imagined items than for those seen with a picture. Overall, these results indicate that FMS affects episodic memory.     

Design and power analysis: n and confidence intervals of means

In this study, we analyzed the validity of the conventional 80% power. The minimal sample size and power needed to guarantee non-overlapping (1-alpha)% confidence intervals for population means were calculated. Several simulations indicate that the minimal power for two means (m = 2) to have non-overlapping CIs is .80, for (1-alpha) set to 95%. The minimal power becomes .86 for 99% CIs and .75 for 90% CIs. When multiple means are considered, the required minimal power increases considerably. This increase is even higher when the population means do not increase monotonically. Therefore, the often adopted criterion of a minimal power equal to .80 is not always adequate. Hence, to guarantee that the limits of the CIs do not overlap, most situations require a direct calculation of the minimum number of observations that should enter in a study.     

Life stressors, emotional avoidance and breast cancer

Two groups of women were assessed in psychological aspects considered by some authors of interest for personal well-being. The sample consisted of 118 women, 58 diagnosed with breast cancer and 60 healthy women, of similar ages and personal circumstances. The purpose of the study was: (a) to explore the existence of stressful life events in the women's history and their degree of subjective distress and (b) to determine whether or not there is an emotional avoidance style in the group of women with breast cancer. The following assessment instruments were employed: the "Cuestionario de Formas de Afrontamiento" (CEA), the Five-Factor Inventory NEO-PI-R, and the State-Trait Anger Inventory (STAXI). The results revealed more stressful vital events in the last two years in the group of women with breast cancer and significant differences in the degree of current distress. They also obtained higher scores in current anger, resignation, and neuroticism.     

Classification of dog barks: a machine learning approach

In this study we analyzed the possible context-specific and individual-specific features of dog barks using a new machine-learning algorithm. A pool containing more than 6,000 barks, which were recorded in six different communicative situations was used as the sound sample. The algorithm's task was to learn which acoustic features of the barks, which were recorded in different contexts and from different individuals, could be distinguished from another. The program conducted this task by analyzing barks emitted in previously identified contexts by identified dogs. After the best feature set had been obtained (with which the highest identification rate was achieved), the efficiency of the algorithm was tested in a classification task in which unknown barks were analyzed. The recognition rates we found were highly above chance level: the algorithm could categorize the barks according to their recorded situation with an efficiency of 43% and with an efficiency of 52% of the barking individuals. These findings suggest that dog barks have context-specific and individual-specific acoustic features. In our opinion, this machine learning method may provide an efficient tool for analyzing acoustic data in various behavioral studies.     

Comparing online and lab methods in a problem-solving experiment

Online experiments have recently become very popular, and--in comparison with traditional lab experiments--they may have several advantages, such as reduced demand characteristics, automation, and generalizability of results to wider populations (Birnbaum, 2004; Reips, 2000, 2002a, 2002b). We replicated Dandurand, Bowen, and Shultz's (2004) lab-based problem-solving experiment as an Internet experiment. Consistent with previous results, we found that participants who watched demonstrations of successful problem-solving sessions or who read instructions outperformed those who were told only that they solved problems correctly or not. Online participants were less accurate than lab participants, but there was no interaction with learning condition. Thus, we conclude that online and Internet results are consistent. Disadvantages included high dropout rate for online participants; however, combining the online experiment with the department subject pool worked well.