Effects of shock intensity and duration on the frequency of biting attack by squirrel monkeys

Squirrel monkeys were periodically exposed to brief tail-shocks in the presence of a rubber tube connected to a pneumatic switch. Biting attack upon this tube was found to be a decreasing function of time since shock delivery and a direct function of shock intensity and duration. These results parallel findings in investigations employing more “naturalistic” social situations, indicating that attack against the inanimate and animate environment is a direct function of the intensity of an aversive stimulus. The results also demonstrate that frequency of biting attack as a datum is sensitive to several experimental manipulations.     

Case-Mixing Effects on Spelling Recognition: The Importance of Test Format

In a multiple-choice spelling recognition test, 56 university students were more accurate on more regular than irregular words, and on lower-case than mixed-case words, with the case mixing effect greater for irregular than regular words. In Experiment 2, the same words were presented singly in correct or incorrect spellings and distortion of word shape was achieved by case mixing (32 subjects) or by alternating the size of lower-case letters within a word (32 subjects). The main effects of regularity and distortion were replicated and the effect of distortion was greater for incorrect than correct stimuli, with correctly spelled words suffering a decrement in accuracy of less than 5 percentage points. Case mixing had a greater effect than size mixing on response latencies. In Experiment 3, with comparable test procedures, case mixing interacted with regularity in the subjects analysis for the multiple choice format, but not the single presentation format. This result indicates that comparisons based on visual configuration may be an artifact of multiple-choice tests.     

Shedding light on photosensitive behaviour in brown planaria (Dugesia Tigrina)

The planarian flatworm is one of the simplest animals to develop two eyecups that enable them to detect the presence and direction of light, which they typically avoid. In this study we assessed responses of planaria to different intensities of light. We found that they exhibited a graded, sigmoidal, photonegative response to light intensity. A two-octave increase in luminance (on the upward slope of the sigmoid) corresponded to a 9% increase in the speed planaria travelled to avoid light.     

Environmental enrichment protects against the effects of chronic stress on cognitive and morphological measures of hippocampal integrity

Chronic stress has detrimental effects on hippocampal integrity, while environmental enrichment (EE) has beneficial effects when initiated early in development. In this study, we investigated whether EE initiated in adulthood would mitigate chronic stress effects on cognitive function and hippocampal neuronal architecture, when EE started one week before chronic stress began, or two weeks after chronic stress onset. Adult male Sprague Dawley rats were chronically restrained (6h/d) or assigned as non-stressed controls and subdivided into EE or non-EE housing. After restraint ended, rats were tested on a radial arm water maze (RAWM) for 2-d to assess spatial learning and memory. The first study showed that when EE began prior to 3-weeks of chronic stress, EE attenuated chronic stress-induced impairments in acquisition, which corresponded with the prevention of chronic stress-induced reductions in CA3 apical dendritic length. A second study showed that when EE began 2-weeks after the onset of a 5-week stress regimen, EE blocked chronic stress-induced impairments in acquisition and retention at 1-h and 24-h delays. RAWM performance corresponded with CA3 apical dendritic complexity. Moreover, rats in EE housing (control or stress) exhibited similar corticosterone profiles across weeks, which differed from the muted corticosterone response to restraint by the chronically stressed pair-housed rats. These data support the interpretation that chronic stress and EE may act on similar mechanisms within the hippocampus, and that manipulation of these factors may yield new directions for optimizing brain integrity and resilience under chronic stress or stress related neuropsychological disorders in the adult.     

Neuroticism and cardiovascular response in women: evidence of effects on blood pressure recovery

Neuroticism is a unifying personality trait that underlies a number of psychosocial risk factors for cardiovascular disease. One means by which Neuroticism may influence health risk is through effects on cardiovascular reactivity and recovery. Eighty-six women scoring high or low in Neuroticism took part in a paired interpersonal stressor task with a laboratory confederate. Conditions differed on the basis of the confederate's interpersonal behavior: hostile, neutral, or friendly. Neuroticism interacted with condition to affect blood pressure recovery such that women high in Neuroticism showed less recovery following hostile interactions and greater recovery following friendly interactions. Main effects of Neuroticism on anger and anxiety reactivity were found. Results indicate that Neuroticism is relevant to cardiovascular health in the context of valenced social interactions. Implications for future study of Neuroticism and interpersonal stressors as risk factors for cardiovascular disease are discussed.     

The effect of metronome pacing on selected aerodynamic patterns of stuttered speech: Some preliminary observations and interpretations

The purpose of this investigation was to provide some preliminary data regarding the effects of metronome pacing on physiological aspects of speech during stuttering. Five aerodynamic measures were chosen as dependent variables: (a) peak intraoral air pressure, (2) intraoral air pressure onset duration, (3) intraoral air pressure offset duration, (4) total intraoral air pressure duration, and (5) peak air flow rate. Five adult stutterers and five adult nonstutterers read a prose passage containing 12 English consonants, each in three syllable-initial stressed positions, during a control condition and experimental condition. In the experimental condition the subjects read the passage while synchronizing one word per beat at 60 beats per minute. The results demonstrated that both stutterers and normals evidenced lower peak pressures and greater pressure durations during metronome pacing. Air flow rates increased for normal subjects and decreased for stutterers in the experimental condition. Dysfluencies recorded during the control condition were observed to have much more rapid intraoral air pressure onsets when compared with fluent counterparts in the experimental reading. These results were interpreted with reference to Wingate's (1969) modified vocalization hypothesis and Van Riper's (1971) altered timing concept.     

Motivational aspects of escape from punishment

Punishment and escape were studied simultaneously by allowing a subject to escape from a stimulus situation in which responses were punished, into a stimulus situation in which responses were not punished. The frequency of the punished responses was found to be an inverse function of the intensity of punishment, whereas the frequency of the escape response was a direct function of the intensity of punishment. Both of these functions were obtained under three different schedules of food reinforcement. The strength of the escape behavior was evidenced by (1) the emergence of the escape response even when the frequency of food reinforcement decreased as a consequence of the escape response, (2) the maintenance of the escape response by fixed-interval and fixed-ratio schedules of escape reinforcement, and (3) the occurrence of escape responses at intensities of punishment that otherwise produced only mild suppression of the punished response when no escape was possible. This last finding indicates that a subject may be driven out of a situation involving punishment even though the punishment is relatively ineffective in suppressing the punished responses when no escape is possible.     

Is pressure stressful? The impact of pressure on the stress response and category learning

We examined the basic question of whether pressure is stressful. We proposed that when examining the role of stress or pressure in cognitive performance, it is important to consider the type of pressure, the stress response, and the aspect of cognition assessed. In Experiment 1, outcome pressure was not experienced as stressful but did lead to impaired performance on a rule-based (RB) category-learning task, but not on a more procedural information-integration (II) task. In Experiment 2, the addition of monitoring pressure resulted in a modest stress response to combined pressure and impairment on both tasks. Across experiments, higher stress appraisals were associated with decreased performance on the RB, but not on the II, task. In turn, higher stress reactivity (i.e., heart rate) was associated with enhanced performance on the II, but not on the RB, task. This work represents an initial step toward integrating the stress cognition and pressure cognition literatures and suggests that integrating these fields may require consideration of the type of pressure, the stress response, and the cognitive system mediating performance.     

The effects of student gender,race, and achievement on career exploration advice given by canadian preservice teachers

This study investigated the effects of gender, race, and achievement on ratings of appropriateness of occupations and classifications of occupations (people, data, things) suitable for future exploration by ninth-grade students. The subjects (N=125; 106 females, 19 males), advanced undergraduate education students, were each asked to evaluate a case folder in which gender (female, male, not stated), race (Native, non-Native), and achievement (higher average, lower average) were systematically varied. Subjects gave ratings of appropriateness for future exploration of occupations on 5-point Likert-type scales. The occupations rated also represented three classifications (data, people, things), yielding a second dependent variable. Analysis was accomplished using two four-way analyses of variance. The attribute most influencing ratings was achievement. However, the three-way interactions of gender, race, and achievement limit direct interpretation of the data, and suggest that complex combinations of student attributes influence teachers. The limitations of the present study are emphasized; the implications for advising young women and for future research are discussed.