High familiarity enhances visual change detection for face stimuli

Does high familiarity with a face enable particularly efficient visual processing? In three experiments, we presented briefly and successively two pairs of faces (either famous or recently learned), masking each presentation. Between the first and the second presentations, one face changed, and the task was to locate this change. Performance was significantly better when the change involved a famous face. This superfamiliarity effect was found only for changes occurring in the left visual field and was abolished by inverting the faces. Extended prior study of the recently learned faces did not improve performance with these stimuli. The results suggest that superfamiliarity promotes highly efficient visual processing and may especially activate a configural mode of analysis.     

Calcium signaling in mitral cell dendrites of olfactory bulbs of neonatal rats and mice during olfactory nerve Stimulation and beta-adrenoceptor activation

Synapses formed by the olfactory nerve (ON) provide the source of excitatory synaptic input onto mitral cells (MC) in the olfactory bulb. These synapses, which relay odor-specific inputs, are confined to the distally tufted single primary dendrites of MCs, the first stage of central olfactory processing. beta-adrenergic modulation of electrical and chemical signaling at these synapses may be involved in early odor preference learning. To investigate this possibility, we combined electrophysiological recordings with calcium imaging in olfactory bulb slices prepared from neonatal rats and mice. Activation of ON-MC synapses induced postsynaptic potentials, which were associated with large postsynaptic calcium transients. Neither electrical nor calcium responses were affected by beta-adrenergic agonists or antagonist. Immunocytochemical analysis of MCs and their tufted dendrites revealed clear immunoreactivity with antibodies against alpha1A (Cav2.1, P/Q-type) and alpha1B (Cav2.2, N-type), but not against alpha1C (Cav1.2, L-type) or alpha1D (Cav1.3, L-type) calcium channel subunits. Moreover, nimodipine, a blocker of L-type calcium channels, had no effect on either electrical or calcium signaling at ON-MC synapses. In contrast to previous evidence, we concluded that in neonatal rats and mice (P5-P8), mitral cells do not express significant amounts of L-type calcium channels, the calcium channel type that is often targeted by beta-adrenergic modulation. The absence of beta-adrenergic modulation on either electrical or calcium signaling at ON-MC synapses of neonatal rats and mice excludes the involvement of this mechanism in early odor preference learning.     

Accurate referential communication and its relation with private and social speech in a naturalistic context

Research into human communication has been grouped under two traditions: referential and sociolinguistic. The study of a communication behavior simultaneously from both paradigms appears to be absent. Basically, this paper analyzes the use of private and social speech, through both a referential task (Word Pairs) and a naturalistic dyadic setting (Lego-set) administered to a sample of 64 children from grades 3 and 5. All children, of 8 and 10 years of age, used speech that was not adapted to the decoder, and thus ineffective for interpersonal communication, in both referential and sociolinguistic communication. Pairs of high-skill referential encoders used significantly more task-relevant social speech, that is, cognitively more complex, than did low-skill dyads in the naturalistic context. High-skill referential encoder dyads showed a trend to produce more inaudible private speech than did low-skill ones during spontaneous communication. Gender did not affect the results.     

Effects of grouping and attention on the perception of causality

Beyond perceiving patterns of motion in simple dynamic displays, we can also perceive higher level properties, such as causality, as when we see one object collide with another object. Although causality is a seemingly high-level property, its perception--like the perception of faces or speech--often appears to be automatic, irresistible, and driven by highly constrained and stimulus-driven rules. Here, in an exploration of such rules, we demonstrate that perceptual grouping and attention can influence the both perception of causality in ambiguous displays. We first report several types of grouping effects, based on connectedness, proximity, and common motion. We further suggest that such grouping effects are mediated by the allocation of attention, and we directly demonstrate that causal perception can be strengthened or attenuated on the basis of where observers are attending, independent of fixation. Like Michotte, we find that the perception of causality is mediated by strict visual rules. Beyond Michotte, we find that these rules operate not only over discrete objects, but also over perceptual groups, constrained by the allocation of attention.     

Boundary distortions for neutral and emotional pictures

In two experiments, we examined Safer, Christianson, Autry, and Osterlund's (1998) claim that when emotional material is remembered, tunnel memory (i.e., the tendency to remember less of a scene than was actually shown) occurs. In Experiment 1, 81 undergraduate students drew photographs from memory after having briefly seen either four neutral or four emotional photographs. Both neutral and emotional drawings revealed boundary extension (i.e., the tendency to remember more of a scene than was actually shown). Experiment 2 relied on the camera distance paradigm (Intraub, Bender, & Mangels, 1992). In a recognition test, 60 undergraduate students judged the camera distance of previously seen neutral or emotional photographs. The majority of them demonstrated accurate judgments and neither extended nor restricted picture boundaries. Those participants who made an error more often displayed a boundary extension than a tunnel memory error. Taken together, our results suggest that boundary extension for neutral and emotional photographs is a more robust phenomenon than its counterpart, tunnel memory.