Verbal and Numerical Expressions of Probability: "It's a Fifty-Fifty Chance"

When estimating risks, people may use "50" as an expression of the verbal phrase "fifty-fifty chance," without intending the associated number of 50%. The result is an excess of 50s in the response distribution. The present study examined factors determining the magnitude of such a "50 blip," using a large sample of adolescents and adults. We found that phrasing probability questions in a distributional format (asking about risks as a percentage in a population) rather than in a singular format (asking about risks to an individual) reduced the use of "50." Less numerate respondents, children, and less educated adults were more likely to say "50." Finally, events that evoked feelings of less perceived control led to more 50s. The results are discussed in terms of what they reveal about how people express epistemic uncertainty. Copyright 2000 Academic Press.     

The effect of imipramine and trazodone on the re-uptake of (3H) serotonin by thrombocytes in patients with endogenous depression: changes in antidepressive therapy

The inhibitory potencies of imipramine (IC50-values for IMI) and trazodone (IC50-values for TRA) on platelet [3H]serotonin uptake were measured in depressed patients. The IC50-values for IMI in patients was shown to be higher (P less than 0.01) than in controls. The IC50-values for TRA in patients were lower (P less than 0.01) than found in platelets from controls. These alterations were not accompanied by the significant decrease of a density of platelet [3H]imipramine binding sites. Drug treatment led to the normalization of the IC50-values for IMI and to the partial increase of the IC50-values for TRA. There was a negative correlation of IC50-values for TRA and severity of depressive symptoms evaluated by the Hamilton Depression Rating Scale. The results support the hypothesis that the mechanisms of the regulation of [3H]serotonin uptake sensitivity to IMI and TRA in patients are different.     

Velocity Toward Goal Attainment in Immediate Experience as a Determinant of Affect

An experiment tested a model in which affect reflects rate of movement (velocity) toward one's behavioral goal. Participants responded to an ambiguous task and received false feedback regarding their performance. The pattern of feedback either remained fairly constant at 50% correct, went from low incidence of correct to 50% correct across trials, or went from high incidence of correct to 50% correct across trials. Self-reported mood change (from before the task to the point at which all groups received 50% correct) took the following pattern: Participants moving from frequent correct to 50% correct (low velocity) changed to less positive mood, whereas those moving from infrequent correct to 50% correct (high velocity) tended to change to more positive mood. Discussion centers on convergence between these findings and those of previous research.     

An Analysis of Speech Disfluencies of Turkish Speakers Based on Age Variable

The focus of this research is to verify the influence of the age variable on fluent Turkish native speakers’ production of the various types of speech disfluencies. To accomplish this, four groups of native speakers of Turkish between ages 4–8, 18–23, 33–50 years respectively and those over 50-year-olds were constructed. A total of 84 participants took part in this study. Prepared and unprepared speech samples of at least 300 words were collected from each participant via face-to-face interviews that were tape recorded and transcribed; for practical reasons, only the unprepared speech samples were collected from children. As a result, for the prepared speech situation, there was no statistically significant difference in terms of age in the production rates of filled gaps, false starts, slips of the tongue and repetitions; however, participants in the over 50-year-old group produced more hesitations and prolongations than participants in the 18–23 and 33–50-year-old groups. For the unprepared speech situation, age variable was not effective on the production rates of filled gaps. However, 4–8 and over 50-year-old participants produced more hesitations and prolongations than the 18–23 and 33–50-year-old groups. 4–8-year-old children produced more slips of the tongue than the 18–23 and 33–50-year-old groups, and more false starts and repetitions than the participants in the other three age groups (18–23, 33–50, over 50). Further analyses revealed more extensive insights related to the types of disfluencies, the position of disfluencies, and the linguistic units involved in disfluency production in Turkish speech.     

Measuring reaction times in healthy probands before and following a single dose of psychotropic drugs

A single dose of Clomipramin, 50 mg; Amitriptylin, 50 mg; Desipramin, 50 mg; Imipramin, 50 mg; Diazepam, 10 mg; Carbamazepin, 200 mg; Haloperidol, 3 mg; were each administered orally, and Clomipramin, 25 mg was administered intravenously, and reaction times were measured and compared with those obtained after administering a placebo. The statistical examination was conducted using Wilcoxon's test. In the case of Amitriptylin, Diazepam, and Haloperidol, there was a statistically significant reduction in the reaction times.     

Response probabilities and “same-different” reaction times

A “same-different” reaction-time (RT) task with multidimensional stimuli was used with a 50:50 and a 75:25 proportion of “different” to “same” response. The “different” RTs to each dimension were similar for the two proportions. However, the “same” RT in the 50:50 condition was faster than the “same” for the 75:25 condition and faster than the slowest “different” RT. Interpretations of the results in terms of response bias and processing criteria are offered.     

Another inexpensive,efficient, solid state shock scrambler

This paper describes an inexpensive, solid state shock scrambler. The circuit employs TTL logic and mercury-wetted relays for quiet, reliable operation. The unit can control shock presentation to 16 grids and operates with an efficiency of 50%; for example, on any given clock pulse, 50% of the grids are positive and the other 50%, negative.     

Choice between reliable and unreliable reinforcement alternatives revisited: Preference for unreliable reinforcement

Pigeons' choices between a reliable alternative that always provided food after a delay (i.e., 100% reinforcement) and an unreliable one that provided food or blackout equally often after a delay (i.e., 50% reinforcement) was studied using a discrete-trials concurrent-chains procedure modified to prevent choice between alternatives following a blackout outcome. Initial links were fixed-ratio 1 schedules, and terminal links were fixed-time schedules. Stimuli presented during the terminal-link delays were correlated with the food and blackout outcomes. In Experiment 1, terminal-link durations were varied. With short terminal links (i.e., 10 s), 6 of 8 subjects showed strong preference for the 50% side. As terminal-link duration increased to 30 s, preference, regardless of direction, became less extreme. In Experiment 2, the side-key location of the 50% and 100% alternatives was reversed for 3 subjects. Preference for the 50% alternative reoccurred following the key reversal. When a 5-s separation was subsequently interposed between the initial and terminal links for both alternatives, all birds reversed to a preference for the 100% side. In general, the strong preference for the 50% side was qualitatively consistent with the expectation that the procedure enhanced the conditioned-reinforcement effectiveness of the food-associated terminal-link stimulus on the 50% side. Implications of the results for various accounts of choice of the 50% alternative are discussed.     

Effects of timeout on a discrimination between fixed-ratio schedules

A discrimination was established between two fixed-ratio schedules of reinforcement. In one, fixed ratio 25, the reinforcer was delivered on the twenty-fifth response; on the other, fixed ratio 50, the fiftieth response was reinforced. In the first component of a chain, either fixed ratio 25 or fixed ratio 50 was randomly programmed on the center key of a three-key pigeon box. Reinforcement of a single peck on the side key was contingent upon discriminating which schedule had just been completed on the center key. During test trials, a timeout was introduced after the first response on fixed ratio 25 and after either the first or twenty sixth response on fixed ratio 50. When the timeout followed the first response on fixed ratio 25 and fixed ratio 50, the accuracy of the discrimination was unaffected. When the timeout followed the first response on fixed ratio 25 and the twenty sixth response on fixed ratio 50, the accuracy of the discrimination decreased rapidly to chance as a function of the duration of the timeout. The loss of discrimination was primarily due to errors after fixed ratio 50 was completed. The timeout appears to weaken the control over the choice response by the response-produced stimuli which preceded the timeout. The results are consistent with the interpretation that the discrimination between fixed ratio 25 and fixed ratio 50 is maintained by chaining of response-produced stimuli within the ratio cycle.     

实质取样对因果强度估计的影响

使用单个目标原因和单个效果的图形集中呈现范式协变关系探讨实质取样增量（12.5%< 50%< 87.5% <100%）对大学生被试因果强度估计的影响。实验结果显示：1）实质取样增加在Power-PC=.50和1协变关系上都导致高估计,在Power-PC=0的协变关系上导致低估计;2）相同实质取样增量对被试在Power-PC=.50（1）协变关系上强度估计的影响符合一次（二次）函数假设。结果说明高实质取样促使被试做出符合理性预期的强度估计,混合假设可以解释被试的强度估计偏离Power-PC值的现象。     

‘Shh … quiet! Here they come.’ Black employees as targets of office gossip

This study explored black employees’ experiences of racial profiling by their white peers through the medium of gossip at a historically white, South African university. Participants consisted of 24 black employees (males = 50%, females = 50%; support staff = 50%, academic staff = 50%). The employees completed a semi-structured interview that elicited their perceptions of the settings in which gossip about black employees occurred, the perceived intentions of such gossip, and their responses to it. The data obtained was thematically analysed. Findings suggested that the gossip targeted black employees who were absent from meetings, and that such gossip undermined the work performance and morale of these employees.     

Can attention give a left-ear advantage for verbal stimuli?

Three independent groups of 8 subjects listened monaurally to a randomized list of 50 common and 50 rare words and responded ‘yes’ to rare words. Responses were analyzed for correct identifications of rare words. A 50:50 group heard an equal number of words in right and left ears and gave a small but non-significant right-ear superiority. A 66:34 group heard nearly twice as many words in the right ear as the left and gave a significant right-ear superiority. A 34:66 group heard nearly twice as many words in the left ear as the right and gave a significant left-ear superiority. Responses were also analyzed according to signal-detection theory. Implications are discussed for theories of ear advantages.     

Signalled and unsignalled avoidance impairments following noradrenaline depletion with DSP4: An hypothesis incorporating and associative and a non-associative factor

Four experiments were performed to investigate the effect of a single prior administration of the selective noradrenaline neurotoxin, DSP4 (50 md/kg, i.p.), upon signalled and unisgnalled variations of the two-way active avoidance procedure. Noradrenaline depletio following DSP4 caused a significant impairment in the acquisition but not in the retention of signalled avoidance. Two unsignalled discrete trial avoidance procedures were used, one of which the 50/10 procedure, was designed to be considerably more difficult than the other, the 50/40 procedure. DSP4- treated rats were found to be impaired on the difficult 50/10 task but not on the 50/40 task. It was also shown that the DSP4 group in the 50/10 experiment made fewer crossings that did not result in shock postponement ('nonreinforced' or intertrial crossings) while in the 50/40 experiment the DSP4 group in the 50/10 experiment made fewer crossings that did not result in shock postponement ('nonreinforced' or 'intertrial' crossings) while in the 50/40 experiment the DSPS group made more 'intertrial' crossings. Response latencies were not significantly altered as a result of the treatment in both instances. The results of the present experiments in conjunction with much accumulate evidence from several other investigations were assimilated in order to develop an hypothesis to account for the consistent signalled two-way avoidance deficits resulting from DSP4 administration. This hypothesis incorporates two main components: (1) It may be that DSP4-treated rats are unable to develop the correct coping behaviour required in the stressful task confronting it, i.e. they fail to make the appropriate crossing (running) respose whether an escape or an avoidance response; (2) It is possible that DSP4-treated rats may fail to associate adequately a successful avoidance response with either the tone that signals shock or the postponement of shock.     

Reduced P50 auditory sensory gating response in professional musicians

Evoked potential studies have demonstrated that musicians have the ability to distinguish musical sounds preattentively and automatically at the temporal, spectral, and spatial levels in more detail. It is however not known whether there is a difference in the early processes of auditory data processing of musicians. The most emphasized and studied early process, especially for neuropsychiatric purposes, is sensory gating. The suppression percentage of the midlatency auditory evoked potential P50, and rarely the N100, wave is used for sensory gating studies. Our aim in this study was to investigate whether there was a difference in the auditory P50 and N100 suppression of control subjects who were professional musicians with no psychiatric problems. 34 professional musicians and 19 non-musicians (the control group) were included in this study. P50 and N100 measurements were taken, the suppression percentage of P50 and N100 was calculated and the results compared. Musicians showed significantly less P50 suppression when compared to non-musicians. There was no significant difference for N100 suppression. What the decreased P50 suppression in musicians when compared to non-musician subjects means, when we also take into account that N100 suppression is not decreased, and how it may contribute to the music perception and production processes of these persons is discussed.     

Contrast between what is expected and what occurs increases pigeon’s suboptimal choice

Animal Cognition - When pigeons are given a choice between 50% signaled reinforcement and 100% reinforcement they typically do not choose optimally, sometimes even preferring 50% reinforcement....     

Resilience from Childhood Stressors: The Role of Cultural Resilience,Ethnic Identity,and Gender Identity

This study examined the potential influence of cultural resilience, ethnic identity, and gender identity on resilience processes across diverse racial/ethnic groups of young women. A sample of 200 women who attended a large state university were studied, of whom 50 self-identified as White, 50 as African American, 50 as Asian or Asian American, and 50 as Latina. Results indicated significant racial/ethnic differences in childhood stressors experienced by the women such that African American, Asian/Asian American, and Latina women reported more overall childhood stressors and more stress associated with racism and sexism than their White counterparts. Furthermore, ethnic identity search and an androgynous gender identity contributed to greater resilience. Implications for research and practice are discussed.     

To Forget or Not to Forget: The Effect of Probability of Test on Directed Forgetting

Two experiments investigated how individuals use explicit memory cues that designate different probabilities of test. As in typical directed forgetting studies, subjects received words explicitly cued as having either a 0% or a 100% chance of being on a subsequent memory test (i.e. forget and remember cues, respectively). In addition, some words were explicitly cued as having the potential to be either forgotten or remembered (i.e. a 50% cue). Recall of 50% words was between that of 0% and 100% words. In addition, the presence of 50% words lowered recall of the 100% words compared to that of a control group that did not receive the 50% words, but received the same number of 100% words. A think-aloud task indicated that these results were due to the 50% words being treated like either 100% or 0% words at encoding. The results are discussed in terms of the effect of different probabilities of test on the strategic processing and representation of information.     

Primary and secondary reinforcers as distinctive cues which acquire information value in partial-reinforcement discrimination training

To assess the cue as opposed to incentive effect of reward, rats were trained on an easy visual discrimination with food contingent on 50 or 100% of the correct responses, and white-noise contingent on 0, 50 or 100% of these responses. Additionally, the 50% food and noise schedules were structured for different groups to produce positive, zero, or negative correlations of the two events. Although the addition of noise did not affect learning with 100% food, the slower learning observed with 50% food was increasingly offset by greater percentages of noise, with the 50% groups showing faster learning under the negative than zero correlation and faster under the zero than positive correlation. Together with supporting speed data, these results indicate that a “neutral” stimulus can be substituted for food with little loss in performance. Consequently, the reinforcing effect of food is attributed in part to its function as a cue which, like noise, can increase the discriminability of the alternatives and provide information about the correctness of the response.     

Stress, locus of control, and psychological status in black South African migrants

The aim of this study was to investigate the specific impact of a major migration-related stressor on the psychological functioning of Black South African migrants who had been coerced to migrate from their indigenous residence to an area designated by the South African government. Scales measuring stress, locus of control, and psychological status were administered to a sample of 50 involuntary farm migrants, 50 "voluntary" farm migrants, 50 "black spot" migrants, and 50 non-migrants. Subjects were male and female adults aged between 35 and 45 years. Results indicated that migrants perceived more stress and were more psychologically distressed than nonmigrants. This distress was particularly associated with the stressor lose home. Farm migrants perceived more external control than black spot and nonmigrant groups.     

Fifty years of dichotic listening research - still going and going and…

This year celebrates 50 years of research in auditory laterality and hemispheric asymmetry, using a dichotic listening approach. The discovery of the "right ear advantage" in 1961 by Doreen Kimura to dichotic presentations of phonetic stimuli paved the way for new studies of how speech perception and related language processes are lateralized in the human brain. The articles in this special issue, celebrating the first 50 years of dichotic listening research, reveal both the breadth and depth of current research, with contributions spanning from basic research to clinical applications, from behavioral studies to studies using advanced neuroimaging techniques, and with contributions from all over the world. It is my hope as Guest Editor that the next 50 years will be as productive as the first 50 years.