Disrupted memory inhibition in dementia of Alzheimer’s type

Cognitive inhibition has been suggested to deteriorate in Alzheimer’s disease. While numerous studies with different experimental paradigms found evidence on impaired inhibition in attention and memory, evidence in favour of intact memory inhibition has been reported with regard to the phenomenon of retrieval-induced forgetting (Moulin et al., 2002). Here, we adapted the previously used paradigm in order to reduce the contribution of non-inhibitory processes and examined whether retrieval-induced forgetting could still be observed in a sample of participants with diagnosed Alzheimer’s disease. In contrast to the previous finding, we found that retrieval-induced forgetting only occurred in an age-matched control group. These results suggest that inhibitory deficits in Alzheimer’s disease also generalize to memory inhibition that resolves interference occurring during retrieval, whereas effects of retrieval-induced forgetting may still occur when non-inhibitory causes, such as, blocking by previously retrieved content, are not precluded.     

A parent-report scale of behavioral inhibition: Validation and application to preschool-age children who do and do not stutter

PurposeThis two-part (i.e., Study 1, Study 2) study investigated behavioral inhibition (BI) in preschool-age children who do (CWS) and do not (CWNS) stutter. The purpose of Study 1 was to develop the Short Behavioral Inhibition Scale (SBIS), a parent-report scale of BI. The purpose of Study 2 was to determine, based on the SBIS, differences in BI between CWS and CWNS, and associations between BI and CWS’s stuttering frequency, stuttering severity, speech-associated attitudes, and stuttering-related consequences/reactions.MethodParticipants in Study 1 were 225 CWS and 243 CWNS with the majority of them being included in Study 2. In Study 2, a speech sample was obtained for the calculation of stuttering frequency and severity, and the parents of a subset of CWS completed the Communication Attitude Test for Preschool and Kindergarten Children Who Stutter (Vanryckeghem & Brutten, 2007), and the Test of Childhood Stuttering Disfluency-Related Consequences Rating Scale (Gillam, Logan, & Pearson, 2009).ResultsStudy 1 analyses indicated that SBIS is a valid and reliable tool whose items assess a single, relatively homogeneous construct. In Study 2, CWS exhibited greater mean and extreme BI tendencies than CWNS. Also CWS with higher, compared to CWS with lower, BI presented with greater stuttering frequency, more severe stuttering, greater stuttering-related consequences, and more negative communication attitudes (for CWS older than 4 years of age).ConclusionFindings were taken to suggest that BI is associated with early childhood stuttering and that the SBIS could be included as part of a comprehensive evaluation of stuttering.     

Do behavioral measures of self-control assess construct-level variance?

A wide range of measures have been used to assess self-control including executive function tasks, delay of gratification tasks, and persistence and willpower tasks. The current study sought to examine the convergent and predictive validity of these measures, provide theoretical backing for why we might or might not expect high correlations between different indicators of the construct, and question whether such measures are assessing construct-level variance. The results largely replicated prior research, with the majority of correlations being small in magnitude and non-significant. Possible interpretations include indicators assessing distinct and unrelated subdomains of self-control, the inappropriate use of measures that maximize within person variance, indicators being plagued by large sources of error variance, or some combination of these.     

Higher inhibitory control is required to escape the innate attraction to effort minimization

Recent evidence suggests humans have an automatic attraction to effort minimization. Yet, how this attraction is associated with response inhibition is still unclear. Here, we used go/no-go tasks to capture inhibitory control in response to stimuli depicting physical activity versus physical inactivity in 59 healthy young individuals. Higher commission errors (i.e., failure to refrain a response to a “no-go” stimulus) indicated lower inhibitory control. Based on the energetic cost minimization theory, we hypothesized that participants would exhibit higher commission errors when responding to physical inactivity stimuli rather than physical activity stimuli. Mixed effects models showed that, compared to physical activity stimuli, participants exhibited higher commission errors when responding to stimuli depicting physical inactivity (odds ratio = 1.59, 95% Confidence Interval = 1.18 to 2.16, p = .003). These results suggest that physical inactivity stimuli might require high response inhibition. This study lends support for the hypothesis that an attraction to effort minimization might affect inhibitory processes in the presence of stimuli related to this minimization. The study pre-registration form can be found at https://doi.org/10.17605/OSF.IO/RKYHB.     

Evolution of Destructive Aggression

Aggression is defined as a mechanism of spacing by means of force or displays. It has evolved independently in different animal groups. The mechanisms underlying it are therefore not homologous throughout the animal kingdom. The phenomenon of aggression is so widespread, however, that strong selection pressures must be responsible for its development along analogous lines. Its most obvious functions are in competition for mates, natural resources, and territories, and in the preservation of group identity in many gregarious species. Aggression is often ritualized so that no damage is done to conspecifics. This ritualization may appear as modification of fighting into a tournament, or as the development of submissive postures which block further aggression in the opponent shortly after the onset of a potentially damaging fight. Animal aggression is preprogrammed by phylogenetic adaptation in well-defined ways, but can be modified by experience. The inborn programs involve motor patterns, innate releasing mechanisms, releasers, motivating mechanisms, and learning dispositions specific for the species. Aggression on this biological level can be observed in humans as intragroup aggression. Certain motor patterns and signals which lead to the release of aggression are universal. Some can even be found in deaf- and blind-born people, proving their innateness. A number of patterns of aggression in man are highly ritualized and - in a way analogous to that found in many animals - mechanisms of control have evolved inhibiting the killing of a conspecific. There are strong indications of the existence of motivating mechanisms within the brain, e.g., in the form of neuronal circuits, that show a degree of spontaneity. The type of destructive aggression which we call war, is a product of cultural evolution. War takes advantage of the given motivational structure of man, including his fear of strangers, which develops in every baby independently of experience and makes men inclined to form closed groups and causes them to be wary of or hostile to strangers. Based on these tendencies, man underwent a process of cultural subspeciation. Groups demarcated themselves from others by custom, erecting communication barriers. The development of languages demonstrates how fast and efficient this process is. Members of the same group, during this process, were defined as the “real man,” outsiders often were to be valued less -or even considered nonhuman. On the basis of this self-indoctrination, cultural codes of conduct developed, which allowed members of other groups to be killed when groups competed for resources. A cultural fiiter of norms was established which demanded killing under defined conditions, and was superimposed upon the biological filter of norms which inhibits the killing of a human being. This results in a conflict of norms, which is universally felt as guilt, since the biological filter of norms, though superimposed, is nonetheless working, particularly in the circumstance of a personal encounter. The more advanced the technique of armament, which allows fast and distant killing, the less the inhibitions are activated. Nonetheless, ritualizations occur on the cultural level. Warfare is sometimes ritualized and conventions are developed to prevent escalation into massacres, or the wholesale destruction of the subjugated enemy. To a great extent, this is certainly a result of our inborn moral code, If nothing like this were given to man our situation would be disastrous indeed. Whether cultural evolution will, in the future, be guided by moral maxims in accord with our human nature is a deeision men must make rationally. Although a ruthless ethnocentrism may bring advantage to a warring group, this may eventually prove fatal to mankind as a whole. In the escalating competition mankind runs the danger not only of exhausting its resources, but of destroying itself with its new weapons. If the outcome were not selfdestruction but domination by one group it would impoverish the diversity of human cultures, and thus seriously cut down man's spectrum of adaptability. War fulfills certain functions, similar to those found in animals. It is mainly a mechanism for preserving and extending one's territory, and a means of getting access to scarce resources. It is therefore dangerous to consider war merely as a pathological form of human behavior because this may distract our attention from the fact that, h order to overcome war, the functions of war have to be fulfilled by nonviolent means. Cultural evolution phenocopies biological evolution, due to similarities in the selection pressures shaping its course. This allows us to define the point of the evolutionary spiral we are at currently and to predict our future course.     

The medial amygdala: Serotonergic inhibition of shock-lnduced aggression and pain sensitivity in rats

Two aspects of the amygdaloid complex (corticomedial and basolateral) were examined with reference to serotonergic inhibition of shock-induced aggression. Fighting was significantly depressed by serotonergic stimulation (5-HT, 10 μg bilateral) in the corticomedial amygdala while serotonergic blockade (methysergide, 5 μg bilateral) in this region increased levels of fighting. No consistent effects were obtained with serotonergic manipulation of the basolateral amygdala. Further investigation revealed that the state of serotonergic activity in medial amygdaloid sites was associated with concomitant alterations in the animals' sensitivity to footshock. Results are discussed in relation to a) a general inhibitory role of serotonin in behavioural mechanisms and b) a dopaminergic-serotonergic balance for behavioural arousal involving medial amygdaloid nuclei.     

Hyperactivity in Children: A Focus on Genetic Research and Psychological Theories

Hyperactivity has attracted a large amount of research interest in recent years. Here we review developments in genetic research and in research testing psychological theories of the condition. Family, adoptee and twin studies indicate a strong role for genetic factors in the etiology of hyperactivity. Evidence is emerging also from molecular genetic studies, implicating specific genes that may be involved. At the level of cognitive functioning, a divided, focused or sustained attention deficit does not seem to be a core deficit in hyperactivity. Although children with hyperactivity often perform poorly on certain executive function tasks, there is disagreement about the interpretation of these findings. The association reported in some studies between a slow inhibitory process and hyperactivity may reflect a generally slow, variable in speed and inaccurate pattern of responding. Hypotheses about psychological mechanisms such as state regulation or delay aversion provide alternative, and particularly encouraging, interpretations of the findings. We discuss the possible integration of the two lines of research—those of genetic research and research on psychological mechanisms.     

Use of a lag differential reinforcement contingency to increase varied selections of classroom activities

The present study evaluated the effects of a lag differential reinforcement contingency on 2 students' activity selections using reversal designs. Results showed that the lag contingency was responsible for promoting increased novel selections, engagement in diverse activities, and greater progress with respect to programmed academic activities.     

Rate of conditioned reinforcement affects observing rate but not resistance to change

The effects of rate of conditioned reinforcement on the resistance to change of operant behavior have not been examined. In addition, the effects of rate of conditioned reinforcement on the rate of observing have not been adequately examined. In two experiments, a multiple schedule of observing-response procedures was used to examine the effects of rate of conditioned reinforcement on observing rates and resistance to change. In a rich component, observing responses produced a higher frequency of stimuli correlated with alternating periods of random-interval schedule primary reinforcement or extinction. In a lean component, observing responses produced similar schedule-correlated stimuli but at a lower frequency. The rate of primary reinforcement in both components was the same. In Experiment 1, a 4:1 ratio of stimulus production was arranged by the rich and lean components. In Experiment 2, the ratio of stimulus production rates was increased to 6:1. In both experiments, observing rates were higher in the rich component than in the lean component. Disruptions in observing produced by presession feeding, extinction of observing responses, and response-independent food deliveries during intercomponent intervals usually were similar in the rich and lean components. When differences in resistance to change did occur, observing tended to be more resistant to change in the lean component. If resistance to change is accepted as a more appropriate measure of response strength than absolute response rates, then the present results provide no evidence that higher rates of stimuli generally considered to function as conditioned reinforcers engender greater response strength.     

Effects of stop signal modality, stop signal intensity and tracking method on inhibitory performance as determined by use of the stop signal paradigm

In Experiment 1, the effects of stop signal modality on the speed and efficiency of the inhibition process were examined. Stop signal reaction time (SSRT) and inhibition function slope in an auditory stop signal condition were compared to SSRT and inhibition function slope in a visual stop signal condition. It was found that auditory stop signals compared to visual stop signals enhanced both the speed and efficiency of stopping. The modality effects were attributed to differences in the neurophysiological processes underlying perception. However, Experiment 2 demonstrated that the modality difference was larger for 80 dB(A) auditory stop signals than 60 dB(A) auditory stop signals. This effect was reconciled with the suggestion that loud tones are more capable of eliciting immediate arousing effects on motor processes than weak tones and visual stimuli. The second purpose of the present investigation was to explore the utility (and potential advantages) of an alternative way of setting stop signal delay relative to mean reaction time (MRT). The method that was suggested compensates for inter-individual differences in primary task reaction speed by setting stop signal delays as proportions of the subjects' MRT.