Hippocampal stimulation disrupts spatial working memory even 8 h after acquisition

The present experiment used hippocampal stimulation to determine the temporal gradient of consolidation of spatial working memory. Rats were trained to perform a spatial working memory task on a radial maze with 12 arms. Each rat went to the ends of 6 arms to obtain a food reward. After 8 h, the rat chose among all the arms to find the ones not previously chosen (and consequently still having food). During some test sessions, the hippocampus was stimulated electrically either at a current level just high enough to produce an electrophysiological seizure, or at a current level below this seizure threshold. Stimulation occurred at one of five intervals (0 to 8 h) following the completion of the first six choices. During other test sessions, the hippocampus was not stimulated. After seizure stimulation, the number of retroactive errors (returning to arms chosen prior to stimulation) increased at all delay intervals; the number of proactive errors (returning to arms chosen after stimulation) increased only with the delay of 8 h. Subthreshold stimulation had no influence on either type of error. These results indicate that normal hippocampal function is required for the maintenance of spatial information in working memory, and that the time course of consolidation of this information is significantly greater than that seen in other types of memory, or consolidation may not take place at all.     

Training and Research in Counselling

Formal counselling training in Britain began with the preparation of school counsellors in universities and relied largely upon American models. Early courses were highly didactic but over the last decade practical and experiential aspects have taken precedence. Basic counselling training has now been extended into the preparation of many workers, voluntary and professional. Counselling research also had academic origins, but has broadened to include many different work settings. Much of the published research has been in the form of surveys of counselling services, but some detailed studies of process are noted. There is a need for research to be increased, and the gap between research and practice shortened, if counselling is to demonstrate its relevance to contemporary needs.     

Levels of processing and picture memory: the physical superiority effect

Six experiments studied the effect of physical orienting questions (e.g., "Is this angular?") and semantic orienting questions (e.g., "Is this edible?") on memory for unrelated pictures at stimulus durations ranging from 125-2,000 ms. Results ran contrary to the semantic superiority "rule of thumb," which is based primarily on verbal memory experiments. Physical questions were associated with better free recall and cued recall of a diverse set of visual scenes (Experiments 1, 2, and 4). This occurred both when general and highly specific semantic questions were used (Experiments 1 and 2). Similar results were obtained when more simplistic visual stimuli--photographs of single objects--were used (Experiments 5 and 6). As in the case of the semantic superiority effect with words, the physical superiority effect for pictures was eliminated or reversed when the same physical questions were repeated throughout the session (Experiments 4 and 6). Conflicts with results of previous levels of processing experiments with words and nonverbal stimuli (e.g., faces) are explained in terms of the sensory-semantic model (Nelson, Reed, & McEvoy, 1977). Implications for picture memory research and the levels of processing viewpoint are discussed.     

Some effects of color on naming and recognition of objects

In this article, we investigated the role of color in the recognition and naming of everyday objects. In the first experiment we found that color pictures were named faster than black-and-white and that shape information did not facilitate color naming. Experiment 2 was carried out to determine at which stage of object processing the color facilitation occurred. We found that color had no effect on object recognition but did facilitate object naming, even when color was redundant for discrimination. This did not apply to naming abstract shapes. Experiment 3 replicated the findings of Experiment 2 using different objects and colors. The results showed that color could facilitate but not inhibit object naming and did not affect object recognition.     

Effects of luminance and contrast on direction of ambiguous apparent motion

A study is reported of the role of luminance and contrast in resolving ambiguous apparent motion (AM). Different results were obtained for the short-range (SR) and the long-range (LR) motion-detecting processes. For short-range jumps (7.5 min arc), the direction of ambiguous AM depended on brightness polarity, with AM only from white to white and from black to black. But for larger jumps, or when an interstimulus interval (ISI) was introduced, AM was less dependent on polarity, with white often jumping to black and black jumping to white. Two potential AMs were pitted against each other, one carried by a light stimulus and the other by a dark stimulus. The stimulus whose luminance differed most from the uniform surround captured the AM. Visual response to luminance was linear, not logarithmic. When the stimulus was modified to give continuous AM in one direction it was followed by a negative aftereffect of motion only when the spatial displacement was 1 min arc. A larger displacement (10 min arc) gave good AM but no motion aftereffect. Thus only short-range motion adapts motion-sensitive channels.     

Cognitive mechanisms mediating the biasing effects of leader sex on ratings of leader behavior

The present study examined the effects of the sex of the leader, the sex of the rater, and the temporal position of leader performance information on ratings of leader behavior. Male and female subjects listened to an audiotape of a male or female leader and then rated the leader's initiating structure and consideration behaviors. The position of the leader performance information was manipulated by describing the leader as successful before or after raters listened to the audiotape or not presenting raters with the performance information. Analyses indicated that the sex of the leader and/or sex of the rater biased ratings of initiating structure when the performance information was presented after the audiotape and when no leader performance information was presented. Consideration ratings were affected only by the position of the leader performance information. The results are interpreted within a cognitive/implicit sex theory framework. Implications for leadership research are also discussed.Portions of the data analyzed in this study were collected by the second author as part of a master's thesis directed by Joseph A. Sgro.     

Attributes and roles assigned to characters in children's writing: Sex differences and sex-role perceptions

This research examined the creative writing of 180 elementary school children for evidence of sex difference and sex-role perceptions. Stories were analyzed for frequency of male and female characters, attributes, and roles. Writers were equally divided by sex and into three age groups—grades 1–2, 3–4, and 5–6. Results suggest that the total number of characters, roles, and attributes was equivalent. However, the distribution of male and female characters, roles, and attributes differed with male and female writers. Female writers included significantly more female characters and assigned more attributes and roles to these characters. Nevertheless, in the stories of both male and female writers, there was a predominance of male characters and assignment of attributes and roles to male characters. The findings support the development and implementation of a nonsexist curriculum.     

Alternation behavior, spatial discrimination, and reversal disturbances following 6-hydroxydopamine lesions in the nucleus accumbens of the rat

The effects of dopaminergic depletion of the nucleus accumbens was tested in various behavioral tasks such as alternation, spatial discrimination, and reversal learning, and in an extinction paradigm in a T maze. Animals with lesions showed impairment of spontaneous alternation behavior, disturbances in the acquisition of spatial discrimination, and great difficulty in reversing previously learned habits. In the extinction phase, experimental animals are unable to adjust their behavior, and continue to choose the previously reinforced arm of the T maze. It is suggested that the nucleus accumbens plays an important role in the transition of motivation into action, and that dopamine has a facilitatory influence on the mediation of these processes.     

Heart-rate responses of infant rats and guinea pigs to stimulus onset and offset: tests of the generality of a bidirectional effect

To test the generality, across modality and across species, of a bidirectional effect of photic stimulation in infant rats found in previous experiments, two experiments examined the effects on heart rate (HR) of onset and offset of auditory stimulation in rats and of photic stimulation in guinea pigs. Experiment 1 demonstrated a unidirectional, decelerative response in rats 17 and 21 days of age to the onset and offset of a 1-kHz tone, at both low (80 dB) and high (100 dB) intensity levels and at 14 days to the onset of the high-intensity tone. Experiment 2 demonstrated that infant guinea pigs, which unlike infant rats are precocial and not nocturnal, responded to the offset but not to the onset of light, and that this response was decelerative. These results indicated a lack of generality of the bidirectional HR effect, and were discussed in terms of the orienting/defensive reflex distinction.     

Aggressive behavior inhibition by serotonin and quipazine injected into the amygdala in the rat

The effects on aggressive behavior, open-field activity, and pain threshold of bilateral microinjections of serotonin (20 micrograms) and quipazine (20 micrograms), the direct serotonergic receptor agonist, into the cortico-medial amygdala were investigated in Wistar rats. Both drugs significantly prolonged the attack latency in isolated killer rats (predatory aggression model), and suppressed the incidence of aggressive postures/attacks in shock-induced fighting test (affective aggression). The only difference in the open-field behavior was the lower number of central square entries in drug-treated compared to saline-injected rats. None of the substances produced any significant change in jump threshold. It is concluded that stimulation of serotonin receptors within the amygdala produces inhibition of affective and muricidal behavior in isolated rats. The effect does not seem to be dependent on changes in general activity and pain sensitivity.