Plasticity of ability to form cross‐modal representations in infant Japanese macaques

In a previous study, Adachi, Kuwahata, Fujita, Tomonaga & Matsuzawa demonstrated that infant Japanese macaques (Macaca fuscata) form cross‐modal representations of conspecifics but not of humans. However, because the subjects in the experiment were raised in a large social group and had considerably less exposure to humans than to conspecifics, it was an open question whether their lack of cross‐modal representation of humans simply reflected their lower levels of exposure to humans or was caused by some innate restrictions on the ability. To answer the question, we used the same procedure but tested infant Japanese macaques with more extensive experience of humans in daily life. Briefly, we presented monkeys with a photograph of either a monkey or a human face on an LCD monitor after playing a vocalization of one of these two species. The subjects looked at the monitor longer when a voice and a face were mismatched than when they were matched, irrespective of whether the preceding vocalization was a monkey's or a human's. This suggests that once monkeys have extensive experience with humans, they will form a cross‐modal representation of humans as well as of conspecifics.     

Perceived range, perceived velocity, and perceived duration of the body rotating in the frontal plane

We investigated perceived range, perceived velocity, and perceived duration of the body rotating in the frontal plane (in roll). Specifically, to examine how shear to the otoliths in the inner ears and tactile pressure to the trunk affect judgments of range and velocity, in two experiments, we manipulated rotating range (30°–160°), rotating velocity (1.8°/sec to 9.6°/sec), mean tilt of the body (?60°, 0°, and 60°), and exposure to the visual vertical. Thirty-three normal or blindfolded participants made verbal judgments of range, velocity, and duration for each combination of these factors. The exponents of the power functions fitted to these judgments were, as a first approximation, .94, .61, and .84 for range, velocity, and duration, respectively, and perceived velocity was proportional to the ratio of perceived range to perceived duration (r = .91). These results suggest that the vestibular and somatosensory inputs are effective on judgments of range, but less so on judgments of velocity, and that perceived velocity may be determined as a ratio of perceived range to perceived duration. In addition, we found that (1) when the range the body has traveled is constant, the perceived range increases as the objective velocity decreases (proprioceptive τ effect); (2) self-motion through the tilted roll sometimes enlarges perceived range and perceived duration but reduces perceived velocity; and (3) the exposure to the visual vertical reduces variability of judgments for range and velocity and also reduces perceived range and perceived velocity of self-motion within a small range through the vertical roll.     

Long-lasting effects of subliminal affective priming from facial expressions

Unconscious processing of stimuli with emotional content can bias affective judgments. Is this subliminal affective priming merely a transient phenomenon manifested in fleeting perceptual changes, or are long-lasting effects also induced? To address this question, we investigated memory for surprise faces 24 h after they had been shown with 30-ms fearful, happy, or neutral faces. Surprise faces subliminally primed by happy faces were initially rated as more positive, and were later remembered better, than those primed by fearful or neutral faces. Participants likely to have processed primes supraliminally did not respond differentially as a function of expression. These results converge with findings showing memory advantages with happy expressions, though here the expressions were displayed on the face of a different person, perceived subliminally, and not present at test. We conclude that behavioral biases induced by masked emotional expressions are not ephemeral, but rather can last at least 24 h.     

Individual differences in language lateralisation,schizotypy and the remote-associate task

We tested the hypothesis that the level of reduced laterality in language is correlated with the degrees of schizotypal personality in healthy individuals and with their performance in the remote-associate task (RAT). A total of 53 healthy participants completed a schizotypal personality measure of the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE; a questionnaire measuring the level of psychotic proneness), a consonant–vowel–consonant (CVC; requiring the identification of letter trigrams presented tachistoscopically in the left/right visual fields or both), measuring reduced language laterality and a remote-associate task (RAT; requiring to report a word, weakly associated with three cue words). Analysis revealed correlations between CVC and O-LIFE, as well as between CVC and RAT performance. The results suggest that reduced language lateralisation (reduced hemispheric integration) may play a role in schizophrenic language disorganization, as reflected in highly schizotypal individuals, and that hemispheric integration plays a role in the remote-associate task.     

Choice between Single-Response and Multichoice Tasks in Humans

The Psychological Record - The present study examined choice in humans between a single-response task and a task with multiple alternatives (i.e., a multichoice task). The alternatives provided...     

Acquisition of a same-different discrimination task by pigeons (Columba livia)

Four homing pigeons were trained to discriminate two figures simultaneously presented on an LCD screen. The figure was either a rectangle (A) or a square (B), and four combinations of the two figures, AA, AB, BA, BB, appeared in a pseudo-randomized order. The pigeons' task was to peck one of these figures based upon whether the two figures were identical or not. One pigeon successfully learned this discrimination, with proportions of correct responses above 90% in two consecutive sessions. Of the other birds, two performed above chance level but had difficulty meeting a learning criterion of above 80% in two consecutive sessions. All birds achieved this criterion when the combinations of figures presented were reduced to two. Results suggested that learning the present same-different discrimination is within the capacity of pigeons to a certain extent, although there exists considerable individual variation in the pigeons' skills to acquire complex discrimination.     

Categorical and dimensional perceptions in decoding emotional facial expressions

We investigated whether categorical perception and dimensional perception can co-occur while decoding emotional facial expressions. In Experiment 1, facial continua with endpoints consisting of four basic emotions (i.e., happiness-fear and anger-disgust) were created by a morphing technique. Participants rated each facial stimulus using a categorical strategy and a dimensional strategy. The results show that the happiness-fear continuum was divided into two clusters based on valence, even when using the dimensional strategy. Moreover, the faces were arrayed in order of the physical changes within each cluster. In Experiment 2, we found a category boundary within other continua (i.e., surprise-sadness and excitement-disgust) with regard to the arousal and valence dimensions. These findings indicate that categorical perception and dimensional perception co-occurred when emotional facial expressions were rated using a dimensional strategy, suggesting a hybrid theory of categorical and dimensional accounts.     

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.     

Retrieval-induced forgetting in rats

“Retrieval-induced forgetting” in rats was evaluated using a modified spontaneous object recognition test. The test consisted of a sample phase, retrieval or interference phase, and a test phase with 60-min delay period inserted between the phases. Rats were randomly assigned to one of three groups (control, retrieval and interference) and allowed to explore the field in which two different objects (A, B) were placed in the sample phase. In the retrieval phase, two identical objects (B, B), which were the same as one of the objects presented in the sample phase, were placed again. In the interference phase, two identical objects (C, C), which were novel for animals, were placed. In the test phase, two different objects (A, D), one of which was identical to that presented in sample phase (familiar object) and the other was novel, were placed and the time spent exploring each object was analyzed. While the exploration of the novel object was significantly longer than that of the familiar object in rats subjected to the interference phase, rats subjected to the retrieval phase could not discriminate between the familiar and the novel objects at the test phase. These results demonstrate the “retrieval-induced forgetting” phenomenon in a spontaneous object recognition test in rats.     

Human Group Choice in Loss Minimization and Gain Maximization Games

The Psychological Record - College students participated as a group in a point-loss minimization game as well as in a point-gain maximization game. The rule of the maximization game was similar to...