Attention and cue-producing behavior in the monkey

Explicit cue-producing responses were employed to study attending behavior in the monkey. The subjects learned a discrimination based on compound stimuli, a vertical bar embedded on a red ground versus a horizontal bar on a green ground. On some trials only one of the two stimulus components was presented (red versus green or vertical versus horizontal bar), and the animals had the option of responding on the basis of the component presented or transforming it to the compound discriminanda by means of a cue-producing response. Analysis of the choice and cue-producing response behavior showed that (a) both monkeys acquired the discrimination between the compound cues solely on the basis of the color component, (b) mastery of this discrimination did not confer any "habit loading" (discriminative control) on the bar component, and (c) the monkey may prefer to respond on the basis of one component (color) even though it is capable of using both components equally effectively.     

The beneficial effects of meprobamate on delayed response performance in the frontal monkey

Previous studies of antagonistic treatments on delayed response performance by frontal monkeys suffer from a logical flaw in that the treatments may also improve the performance of normal monkeys. In a previous study (Gross and Weiskrantz, 1961) we have shown that meprobamate is without effect on delayed response in normal monkeys, but it does severely depress their discrimination performance. In the current study meprobamate is shown to produce a significant improvement in delayed response in each of three frontal monkeys. Nembutal is also effective. Various interpretations of the results are discussed, the view being favoured that the frontal monkey suffers from an excessive and inappropriately ordered intake of sensory information.     

Choice behavior of rats searching for food

The experiments reported here were designed to determine if several general principles drawn from appetitively motivated discrimination experiments in standard laboratory apparatus might also apply to food-searching behavior under more naturalistic conditions. Food-deprived rats searched for food in an open observation area. Choice behavior after finding food and after not finding food was analyzed. In all cases, not finding food in a possible food location was sufficient to direct subsequent search behavior away from that location for the remainder of the day's test. Finding food had variable effects on subsequent choice behavior, depending on the number of locations that actually contained food and the number of days food was in one location before being shifted to another. The results indicate that the rat's search strategy was influenced by food availability and distribution in ways that are predicted by discrimination learning experiments.     

Data on the role of the frontal cortex in vegetative behavior

A homeostatic conditional reflex (CR) was elaborated to the effect of repeated inhalations in rats of a gas mixture containing 8 per cent oxygen. The effect of the conditional response was opposite to that of the unconditional one. After ablation of the frontal cortex, the conditional reaction disappeared. The repeated administration of 40 mg/kg of histamine resulted in a tolerance to the temperature lowering effect of histamine similar to the habituation. An injection of distilled water brought about dishabituation. Tolerance was not influenced by the ablation of the frontal cortex, but the dishabituating effect of distilled water was absent.     

Effects of d-amphetamine on observing behavior in the squirrel monkey

Four squirrel monkeys were trained to press a lever, which produced stimuli indicating availability or non-availability of reinforcement for pushing a key. Food reinforcements were available for the key response at random intervals with an average rate of 1 per min. When food was available, a single lever response produced a red light behind the key. Reinforcement availabilities and red keylights remained until terminated by a reinforced key response. When reinforcement was not available, each lever response produced a 0.5-sec green light on the key. Except after lever responses, the key remained dark. Under this procedure, lever responses functioned as observing behavior in that they produced discriminative stimuli correlated with the availability or non-availability of reinforcement for key responses. The procedure generated a high rate of responding on the lever, short latencies of the key response after onset of red lights and few responses to the key in the absence of red lights. Intra-muscular d-amphetamine, in doses from 0.125 to 1.0 mg/kg, abolished both observing behavior and key responding for periods that increased as a function of dose. However, both observing and key rates were increased at the smallest dose in two subjects whose performances included responding to the key in the absence of red lights. Results are discussed in relation to previous findings regarding effects of amphetamines on operant behavior and on observing and monitoring performance.     

The roles of orbital frontal cortex in the modulation of antisocial behavior

This article considers potential roles of orbital frontal cortex in the modulation of antisocial behavior. Two forms of aggression are distinguished: reactive aggression elicited in response to frustration/threat and goal directed, instrumental aggression. It is suggested that orbital frontal cortex is directly involved in the modulation of reactive aggression. It is argued that orbital frontal cortex does not "inhibit" reactive aggression but rather may both increase or decrease its probability as a function of social cues present in the environment. Early dysfunction in this function of orbital frontal cortex may be linked to the development of Borderline Personality Disorder. Instrumental aggression is linked to a fundamental failure in moral socialization. However, the available data suggest that the amygdala, but not orbital frontal cortex, is required for functions such as aversive conditioning and passive avoidance learning that are necessary for moral socialization. Psychopathic individuals who present with significant instrumental aggression, are impaired in aversive conditioning and passive avoidance learning and show evidence of amygdala dysfunction. Orbital frontal cortex and the amygdala are involved in response reversal where instrumental responses must be reversed following contingency change. Impairments in response reversal are also seen in psychopathic individuals. However, it remains unclear whether impairment in response reversal per se is associated with antisocial behavior.     

Social touch alters newborn monkey behavior

In humans, infants respond positively to slow, gentle stroking—processed by C-tactile (CT) nerve fibers—by showing reductions in stress and increases in eye contact, smiling, and positive vocalizations. More frequent maternal touch is linked to greater activity and connectivity strength in social brain regions, and increases children’s attention to and learning of faces. It has been theorized that touch may prime children for social interactions and set them on a path towards healthy social cognitive development. However, less is known about the effects of touch on young infants’ psychological development, especially in the newborn period, a highly sensitive period of transition with rapid growth in sensory and social processing. It remains untested whether newborns can distinguish CT-targeted touch from other types of touch, or whether there are benefits of touch for newborns’ social, emotional, or cognitive development. In the present study, we experimentally investigated the acute effects of touch in newborn monkeys, a common model for human social development. Rhesus macaques (Macaca mulatta), like humans, are highly social, have complex mother-infant interactions with frequent body contact for the first weeks of life, making them an excellent model of infant sociality. Infant monkeys in the present study were reared in a neonatal nursery, enabling control over their early environment, including all caregiver interactions. One-week-old macaque infants (N = 27) participated in three 5-minute counter-balanced caregiver interactions, all with mutual gaze: stroking head and shoulders (CT-targeted touch), stroking palms of hands and soles of feet (Non-CT touch), or no stroking (No-touch). Immediately following the interaction, infants watched social and nonsocial videos and picture arrays including faces and objects, while we tracked their visual attention with remote eye tracking. We found that, during the caregiver interactions, infants behaved differently while being touched compared to the no-touch condition, irrespective of the body part touched. Most notably, in both touch conditions, infants exhibited fewer stress-related behaviors—self-scratching, locomotion, and contact time with a comfort object—compared to when they were not touched. Following CT-targeted touch, infants were faster to orient to the picture arrays compared to the other interaction conditions, suggesting CT-targeted touch may activate or prime infants’ attentional orienting system. In the No-touch condition infants attended longer to the nonsocial compared to the social video, possibly reflecting a baseline preference for nonsocial stimuli. In contrast, in both touch conditions, infants’ looked equally to the social and nonsocial videos, suggesting that touch may influence the types of visual stimuli that hold infants’ attention. Collectively, our results reveal that newborn macaques responded positively to touch, and touch appeared to influence some aspects of their subsequent attention, although we found limited evidence that these effects are mediated by CT fibers. These findings suggest that newborn touch may broadly support infants’ psychological development, and may have early evolutionary roots, shared across primates. This study illustrates the unique insight offered by nonhuman primates for exploring early infant social touch, revealing that touch may positively affect emotional and attentional development as early as the newborn period.     

Effect of delay-interval illumination on matching behavior in the capuchin monkey

Experiment 1 demonstrated that delayed matching-to-sample in the capuchin monkey was superior when the delay interval was spent in darkness rather than in moderate illumination. In contrast with previous studies in which the delayed-matching ability of primates appeared limited to 60 sec or less, in the dark condition all subjects showed above-chance matching at a 120-sec delay interval. Experiment 2 verified that darkness during the delay interval can facilitate delayed matching and provided evidence that the effective variable was the illumination level of the delay interval rather than change in illumination, which in Exp. 1 was confounded with illumination level.     

Factor analysis of the frontal systems behavior scale (FrSBe)

The Frontal Systems Behavior Scale (FrSBe), formerly called the Frontal Lobe Personality Scale (FLOPS), is a brief behavior rating scale with demonstrated validity for the assessment of behavior disturbances associated with damage to the frontal-subcortical brain circuits. The authors report an exploratory principal factor analysis of the FrSBe-Family Version in a sample including 324 neurological patients and research participants, of which about 63% were diagnosed with neurodegenerative diseases (Huntington's, Parkinson's, and Alzheimer's diseases). The three-factor solution accounted for a modest level of variance (41%) and confirmed a factor structure consistent with the three subscales proposed on the theoretical basis of the frontal systems. Most items (83%)from the FrSBe subscales of Apathy, Disinhibition, and Executive Dysfunction loaded saliently on three corresponding factors. The FrSBe factor structure supports its utility for assessing both the severity of the three frontal syndromes in aggregate and separately.     

A recruitment theory of simple behavior

A statistical theory of choice is developed using a sequential sampling assumption. Response latency distributions for certain simple reaction-time situations are derived and tested. Both response probability and response latency measures are developed for a two-alternative judgment situation and the relationship between the two measures explored. The sampling parameter is proposed as a means of representing incentive conditions in choice situations and ROC curves are obtained by appropriate manipulations of this parameter. A solution to the overlap problem in simple discrimination-learning situations is also derived.This research was supported in part by a grant from the National Science Foundation. The writer has benefited from discussions with his students, James R. Erickson, James G. Greeno, Duane R. Martin, Kirk H. Smith, and Charles F. Stroebel. For generous suggestions with regard to certain mathematical matters, the writer is indebted to Professors Ingram Olkin, Stephen Orey, and Milton Sobel of the Statistics Department at the University of Minnesota.