The problem of serial order in behavior: Lashley's legacy

In a prescient paper Karl Lashley (1951) rejected reflex chaining accounts of the sequencing of behavior and argued instead for a more cognitive account in which behavioral sequences are typically controlled with central plans. An important feature of such plans, according to Lashley, is that they are hierarchical. Lashley offered several sources of evidence for the hierarchical organization for behavioral plans, and others afterward provided more evidence for this hypothesis. We briefly review that evidence here and then shift from a focus on the structure of plans (Lashley's point of concentration) to the processes by which plans are formed in real time. Two principles emerge from the studies we review. One is that plans are not formed from scratch for each successive movement sequence but instead are formed by making whatever changes are needed to distinguish the movement sequence to be performed next from the movement sequence that has just been performed. This plan-modification view is supported by two phenomena discovered in our laboratory: the parameter remapping effect, and the handpath priming effect. The other principle we review is that even single movements appear to be controlled with hierarchically organized plans. At the top level are the starting and goal postures. At the lower level are the intermediate states comprising the transition from the starting posture to the goal posture. The latter principle is supported by another phenomenon discovered in our lab, the end-state comfort effect, and by a computational model of motor planning which accounts for a large number of motor phenomena. Interestingly, the computational model hearkens back to a classical method of generating cartoon animations that relies on the production of keyframes first and the production of interframes (intermediate frames) second.     

Executive Functions in Children: Associations with Aggressive Behavior and Appraisal Processing

This study investigated whether and how deficits in executive functioning and distortions in appraisal processing are related to subtypes of aggressive behavior. The sample included 83 boys assessed using multi-informant reports and performance measures. Deficits in two executive functions, response inhibition and planning ability were related primarily to reactive aggression. Hostile attributional biases moderated relations between planning ability and proactive and reactive aggression subtypes, with minimal relations between planning deficits and aggression at low levels of hostile attributional bias. As the level of hostile attributional bias increased, the relation between planning deficits and reactive aggression became increasingly large in a positive direction whereas the relation between planning deficits and proactive aggression became increasingly negative. Additionally, hostile encoding moderated the relation between behavioral inhibition and reactive aggressive behavior. Results also suggested a mediational role for response inhibition in the relation between planning ability and reactive aggression.     

Explaining the Relation between Religiousness and Reduced Suicidal Behavior: Social Support Rather Than Specific Beliefs

Religiousness has been associated with decreased risk of suicidal ideation, suicide attempts, and completed suicide, but the mechanisms underlying these associations are not well characterized. The present study examined the roles of religious beliefs and social support in that relation. A survey measuring religiousness, social support, suicidal ideation, and suicide attempts was administered to 454 undergraduate students. Involvement in public, but not private, religious practices was associated with lower levels of both suicidal ideation and history of suicide attempts. Social support mediated these relations but religious beliefs did not. Results highlight the importance of social support provided by religious communities.     

Persistent symptoms among survivors of Hodgkin's disease: an explanatory model based on classical conditioning.

Persistent symptoms of nausea, distress, and vomiting triggered by reminders of cancer treatment were examined among 273 Hodgkin's disease survivors, 1 to 20 years posttreatment. Prevalence rates were high for distress and nausea but low for vomiting. Retrospective report of anticipatory symptoms during treatment was the strongest predictor of persistent symptoms, suggesting that treatment-induced symptoms are less likely to persist if conditioning does not occur initially. Time since treatment was also a significant predictor, with patients more recently treated more likely to experience persistent symptoms. Thus, an explanatory model based on classical conditioning theory successfully predicted presence of persistent symptoms. Symptoms also were associated with ongoing psychological distress, suggesting that quality of life is diminished among survivors with persistent symptoms. Recommendations for prevention and treatment of symptoms are discussed.     

Generalization peak shift for autoshaped and operant key pecks.

Pigeons acquired discriminated key pecking between 528- and 540-nm stimuli by either a response-reinforcer (operant group) or a stimulus-reinforcer (autoshaped group) contingency, with other training-schedule parameters comparable over groups. For the birds in the operant group, key pecks intermittently produced grain in the presence of one hue on the key (positive stimulus) but not in the other (negative stimulus). For the birds in the autoshaped group, pecking emerged when grain was intermittently presented independently of key pecking during one key color but was not presented during the other key color. Two independent contingency assays, peck-location comparisons and elimination of differences in reinforcement rate, confirmed the effectiveness of the two training procedures in establishing operant or respondent control of key pecking. After reaching a 10:1, or better, discrimination ratio between key pecks during the two key colors, the birds received a wavelength generalization test. Criterion baseline key-peck rates were comparable for operant and autoshaped groups prior to testing. On the generalization test, performed in extinction, all birds pecked most at a stimulus removed from the positive training stimulus in the direction away from the negative stimulus. In testing, autoshaped "peak" rates (24.5 to 64.9 pecks per minute) were from 33% to 80% higher than rates in the presence of the training stimuli. Respondent peak shift rarely has been reported heretofore, and never this consistently and robustly. These results further confirm the similarity of perceptual processing in classical and operant learning. They are discussed in terms of Spence's gradient-interaction theory and Weiss' (1978) two-process model of stimulus control.     

Sex differences in the incidence and sonographic characteristics of antipredator ultrasonic cries in the laboratory rat (Rattus norvegicus).

Long-Evans rats (Rattus norvegicus; ns = 10 males and 10 females) in a burrow system responded to a cat in the open area by retreating to a burrow and emitting ultrasounds of 18-27 kHz. Females made more frequent ultrasonic cries, with longer durations of ultrasounds. In a 2nd study (ns = 19 males and 19 females), sonographic analyses confirmed the more frequent vocalizations of females and indicated that the sound pulses of females were reliably shorter in duration and of higher base frequency than those of males. Also, females emitted more pulses per pulse train with shorter within-train interpulse intervals. Six basic pulse forms were determined, and males emitted more (70%) pulses with negatively accelerated descending frequencies than females (25%). The findings indicate that female rats show qualitatively different antipredator vocalizations than do males and add to previous findings of higher levels of female antipredator defensiveness.     

The impact of cognitive interference on performance during prolonged sleep loss

Summary A study was conducted on the effects of off-task cognitions on performance during sleep deprivation. Subjects answered the Thought Occurrence Questionnaire, assessing their proneness to engage in off-task cognitions, and were deprived of sleep for 72 hours, during which they performed a variety of tasks including visual discrimination and three versions of a logical reasoning task in which cognitive load was varied systematically. In addition, every day subjects answered the Cognitive Interference Questionnaire, which taps off-task cognitions during the experiment. Results indicated that subjects who habitually engage in off-task cognitions performed worse during 72 hours of sleep loss than subjects who do not engage in such distracting activities. In addition, it was found that the engagement in off-task cognitions increased during the 72 hours of sleep loss and such an engagement was related to deficits in performance accuracy. The mechanisms of off-task cognitions and sleep loss underlying these effects are discussed.     

Directionality in four Bender-Gestalt figures: III.

Two predictions, viz., that for Austrian non-clinical school children whose left-right reading-writing habits parallel an assumed innate left-right drawing tendency, a clear preference for left-right execution of 4 Bender-Gestalt figures (Nos. 1, 2, 3, 6) would be attained at an earlier age and no plateau would be observed in contrast to Israeli non-clinical school children whose right-left reading-writing habits are in a direction opposite to the assumed innate drawing tendency, were confirmed at significant levels of confidence. In a sub-sample of the Austrian population investigated fathers' educational/occupational level as well as the child's position in his sibship as measures of attention and stimulation in the home do not appear to have any significant influence on preference for direction of drawing.