Rapid volitional control of apparent motion during percept generation

How rapidly can one voluntarily influence percept generation? The time course of voluntary visual–spatial attention is well studied, but the time course of intentional control over percept generation is relatively unknown. We investigated the latter question using “one-shot” apparent motion. When a vertical or horizontal pair of squares is replaced by its 90º-rotated version, the bottom-up signal is ambiguous. From this ambiguous signal, it is known that people can intentionally generate a percept of rotation in a desired direction (clockwise or counterclockwise). To determine the time course of this intentional control, we instructed participants to voluntarily induce rotation in a precued direction (clockwise rotation when a high-pitched tone was heard, and counterclockwise rotation when a low-pitched tone was heard), and then to report the direction of rotation that was actually perceived. We varied the delay between the instructional cue and the rotated frame (cue-lead time) from 0 to 1,067 ms. Intentional control became more effective with longer cue-lead times (asymptotically effective at 533 ms). Notably, intentional control was reliable even with a zero cue-lead time; control experiments ruled out response bias and the development of an auditory–visual association as explanations. This demonstrates that people can interpret an auditory cue and intentionally generate a desired motion percept surprisingly rapidly, entirely within the subjectively instantaneous moment in which the visual system constructs a percept of apparent motion.     

Exploring Culture-Specific Differences in Beliefs about Causes, Kinship and the Heritability of Major Depressive Disorder: The Views of Anglo-Celtic and Chinese-Australians

The aim of this study was to explore cultural differences in causal attributions and beliefs about heritability of major depressive disorder (MDD). Face-to-face interviews with Anglo-Celtic- and Chinese-Australians community members with a family history of MDD were conducted and subjected to a rigorous qualitative analysis, using the computer software NVivo. Sixteen Anglo-Celtic-Australians and 16 Chinese-Australians were interviewed. Both groups believed that a combination of genetic and environmental factors contributed to MDD, that stress was an important cause of MDD, and that coping factors were significant moderators of the impact of stress on MDD. Both cultural groups believed that the causes of MDD affecting multiple family members included a shared family environment and a “contagion effect”, in addition to genetics. Unique to the Chinese-Australian group was the beliefs that parental pressures to exceed academically contributed to MDD; this cultural group also reported beliefs that depression was due to God’s will or alternatively fate, which in turn was related to attributions to feng shui and auspicious dates. This study documented key culture-specific differences in beliefs about causes and inheritance of MDD; such differences have major implications for clinician-patient communication about genetic risk associated with having a family history of MDD.     

La enseñanza práctica de la Psicología: una experiencia de condicionamiento instrumental

RESUMEN

n este informe se presenta una experiencia docente en la que un elevado número de estudiantes de primero de Psicología (140), trabajando en grupos de cinco personas y utilizando unos recursos limitados, consiguieron llevar a cabo un condicionamiento instrumental con ratas en la caja de Skinner, cumpliendo adecuadamente los objetivos metodológicos propuestos. Esta experiencia confirma la posibilidad de realizar prácticas en Psicología a pesar de los numerosos impedimentos que existen para ello, destacados por los autores.     

Defect analysis of Fe3(Al1– x Si x ) alloys by positron-lifetime spectroscopy

The recovery behaviour of vacancy-type defects created at 1000°C in Fe₃(Al_{1– x} Si _x ) alloys has been investigated by positron-lifetime measurements in samples cooled to room temperature by water quenching, air quenching and furnace cooling. In addition, a set of samples was aged for one week at 520°C. After water quenching, measurements reveal a high concentration of thermal vacancies, and from the decrease of the average positron lifetime it is inferred that vacancy recovery is strongly composition-dependent. Greater decreases of the positron lifetime were found for Si-rich samples, suggesting diffusion enhancement as the Si concentration increases. For the Fe₃Al alloy, the retained vacancy concentration depends strongly on the cooling rate. This is related to atomic ordering and a rebuilding of the D0₃ structure.     

El lenguaje de los antropoides

RESUMEN

José Eugenio Ortega presenta este dossier sobre el lenguaje de los antropoides repasando algunos intentos de enseñar lenguaje a chimpancés y recordando la gran influencia del “Proyecto Washoe” en investigaciones posteriores desde distintas perspectivas. A continuación explica la clasificación de orden de los primates y las características que hacen de los chimpancés los sujetos idóneos para este tipo de estudios y aborda la polémica entre los grupos que siguen distintos procedimientos respecto a cuál es la metodología correcta, afirmando que en todos los trabajos de lenguaje de antropoides ha habido fallos en el control de variables. En la última parte explica cuatro posturas de los investigadores a la hora de interpretar los resultados de sus estudios, finalizando con algunas reflexiones en torno a las implicaciones de estos trabajos con relación a los de Darwin y manifestando que el estudio de las capacidades de simbolización de los antropoides puede aportar bastantes datos al problema de la evolución humana.     

Categorical perception of anger is disrupted in alexithymia: Evidence from a visual ERP study

High and low alexithymia scorers were confronted with a modified visual oddball task that allowed the study of categorical perception of emotional expressions on faces. Participants had to quickly detect a deviant (rare) morphed face that shared or did not share the same emotional expression as the frequent one. Expected categorical perception effects, which were also neurophysiologically indexed, showed that rare stimuli were detected faster if they depicted a different emotional expression compared to rare stimuli depicting the same emotional expression than the frequent one. Even if no differences were observed at a behavioural level, high alexithymia scorers evidenced overall delayed neurophysiological responses in components related to the attentional processing of rare emotional faces. Moreover, the categorical perception effects for event-related components associated with the attentional processing were smaller in high alexithymia scorers and were even absent for anger. These results show that high alexithymia scorers present discrimination delays that are already observed at the attentional level.     

ERK1/2 activation is necessary for BDNF to increase dendritic spine density in hippocampal CA1 pyramidal neurons

Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling pathway was responsible for BDNF's effects on spine growth. Slice cultures were transfected with enhanced yellow fluorescent protein (eYFP) by particle-mediated gene transfer, and CA1 pyramidal neurons were imaged by laser-scanning confocal microscopy. We confirmed that BDNF (24 h) increases spine density in apical dendrites of CA1 neurons. The MEK (ERK kinase) inhibitors PD98059 and U0126 completely prevented the increase in spine density induced by BDNF, without having an effect on spine density by themselves. In contrast to its actions on cortical pyramidal neurons, BDNF had minor and rather localized effects on dendritic complexity in hippocampal pyramidal neurons, increasing the total length, but not the branching of apical dendrites within CA1 stratum radiatum, without affecting basal dendrites in stratum oriens. Our results support the hypothesis that the ERK-signaling pathway not only mediates long-term synaptic plasticity and hippocampal-dependent learning, but it is also involved in the structural remodeling of excitatory spine synapses triggered by neurotrophins.     

Simultaneous masking in a dichotic emotion detection task

The present study investigated the possible role of ceiling effects in producing laterality effects of small magnitude in dichotic emotion detection. Twenty two right-handed undergraduate students participated in the present experiment. They were required to detect the presence of a target emotion in the expressions tones of happiness, sadness, anger, and neutrality presented dichotically. Stimuli were adjusted to 70 dB and occurred simultaneously with a white noise mask that had an intensity of 65, 70, 80, or 85 dB. Results showed a left ear advantage (LEA) for the 65 dB mask and a right ear advantage for the 85 dB mask, but only after two testing sessions. The possible existence of a generalized right ear bias that might affect the observed LEA for non-verbal tasks is discussed. Alternative explanations and limitations of the present experiment are also presented.