Effects of incentive on cued recall

Words associated with high monetary incentive were better recalled than those associated with low incentive. This effect was found to depend on differential rehearsal, since it was eliminated or markedly attenuated when manipulations designed to minimize rehearsal were used. High-incentive words are more elaborately or extensively processed than low-incentive words, but they are not processed in a qualitatively different manner. This greater elaboration of processing appears to be limited to those attributes or features believed to be relevant to the subsequent retention test. The implications of these findings for incentive theories are discussed.     

Psychophysical thresholds of face visibility during infancy

The ability to detect and focus on faces is a fundamental prerequisite for developing social skills. But how well can infants detect faces? Here, we address this question by studying the minimum duration at which faces must appear to trigger a behavioral response in infants. We used a preferential looking method in conjunction with masking and brief presentations (300 ms and below) to establish the temporal thresholds of visibility at different stages of development. We found that 5 and 10 month-old infants have remarkably similar visibility thresholds about three times higher than those of adults. By contrast, 15 month-olds not only revealed adult-like thresholds, but also improved their performance through memory-based strategies. Our results imply that the development of face visibility follows a non-linear course and is determined by a radical improvement occurring between 10 and 15 months.     

Effects of manipulating an antecedent event on mathematics response rate

The purpose of this investigation was to assess the effects on performance rate of simply writing the answers to mathematics problems versus verbalizing the problems before making a written response. The subject was an 11-yr-old boy whose response accuracy on mathematics problems was very erratic. Three experiments were conducted, each consisting of three phases. In each first phase, the subject was requested to write the answers to sets of mathematics problems. In the second, he was required to verbalize the problem before writing the answer. In the third phase, the subject was told to write the answer again without prior verbalization. The results indicated that the subject's correct answer rate increased and his error rate decreased as a result of his verbalizing the problems before making a written response. Results further revealed that in the final phase of each experiment, the return to the original conditions, his correct answer rate continued to increase.     

Palatability shift of a salt-associated incentive during sodium depletion

Previous studies of natural palatability-sensitive reactions, elicited from rats by tastes, have indicated that the taste of concentrated NaCl becomes more palatable during states of body sodium depletion. A training procedure based upon “sensory preconditioning” or “irrelevant incentive” designs was used here to establish gustatory conditioned labels (quinine or citric acid) for either NaCl or fructose while rats were in a normal physiological state. Experiment 1 replicated demonstrations by others that gustatory conditioned labels for salt can attract and act as independent incentives during the salt appetite induced by sodium depletion. Experiment 2 used the taste reactivity measure to show that the enhanced palatability of the taste of NaCl transfers to produce enhanced palatability of the taste of the isolated conditioned label for salt in a state-dependent fashion. These results offer further support for the proposition that conditioned incentives not only predict hedonic events to follow, but themselves become attributed with the hedonic properties of their reinforcers.     

Short-term memory in the rhesus monkey: A behavioral analysis of delayed-response performance

This study obtained quantitative data on the bodily orientations of rhesus monkeys in a delayed-response task and determined whether such orientations mediate the correct response in a choice trial. The basic task was a two-key chain schedule with the key leading to food signaled in the initial component. During the subsequent delay interval, the signal was removed, but it was necessary that one of the keys be pressed to advance the schedule to the terminal choice component. The position of the key pressed thus indicated orientation during the delay interval. When the monkeys had free access to the left and right keys, they tended to press the key leading to food throughout the chain schedule components and received food on more than 85% of the trials, even when the delay was extended to 20 seconds. However, when orientation toward the food key was disrupted by forcing the monkeys to press an extraneous center key during the delay, choice performance deteriorated. Requiring the center key presses early, rather than late, in the delay component had a strong disruptive effect. The relation of the results to the mediating coding-response hypothesis is discussed.     

Effects of manipulating valence and arousal components of mood on specificity of autobiographical memory

An important cognitive deficit in clinical depression is the inability to be specific in recalling personal memories, a phenomenon coined "overgeneral memory" by Williams and Broadbent. Although there is general consensus that overgeneral memory is not state-dependent, most of the evidence originates from studies of this effect in clinical populations. The two components of mood, valence and arousal, were manipulated to examine their influence on memory specificity in a nonclinical sample of university undergraduate students. In Exp. 1, a Velten procedure was used to induce elated, depressed, or neutral mood states. No difference was found in autobiographical memory specificity among the three groups. In Exp. 2, high and low arousal states were induced through physical exercise. A low arousal state resulted in an increased proportion of overgeneral memories, suggesting that this memory phenomenon may be influenced by the arousal component of mood.     

Sex differences in the neural underpinnings of social and monetary incentive processing during adolescence

The brain’s reward system undergoes major changes during adolescence, and an increased reactivity to social and nonsocial incentives has been described as a typical feature during this transitional period. Little is known whether there are sex differences in the brain’s responsiveness to social or monetary incentives during adolescence. The aim of this event-related potential (ERP) study was to compare the neurophysiological underpinnings of monetary and social incentive processing in adolescent boys versus girls. During ERP recording, 38 adolescents (21 females, 17 males; 13–18 years) completed an incentive delay task comprising (a) a reward versus punishment condition and (b) social versus monetary incentives. The stimulus-preceding negativity (SPN) was recorded during anticipation of reward and punishment, and the feedback P3 (fP3) along with the feedback-related negativity (FRN) after reward/punishment delivery. During anticipation of social punishment, adolescent boys compared with girls exhibited a reduced SPN. After delivery, male adolescents exhibited higher fP3 amplitudes to monetary compared with social incentives, whereas fP3 amplitudes in girls were comparable across incentive types. Moreover, whereas in boys fP3 responses were higher in rewards than in punishment trials, no such difference was evident in girls. The results indicate that adolescent boys show a reduced neural responsivity in the prospect of social punishment. Moreover, the findings imply that, once the incentive is obtained, adolescent boys attribute a relatively enhanced motivational significance to monetary incentives and show a relative hyposensitivity to punishment. The findings might contribute to our understanding of sex-specific vulnerabilities to problem behaviors related to incentive processing during adolescence.     

Effects of social support visibility on adjustment to stress: experimental evidence

Previous fieldwork has suggested that visible social support can entail an emotional cost and that a supportive act is most effective when it is accomplished either (a) outside of recipients' awareness or (b) within their awareness but with sufficient subtlety that they do not interpret it as support. To investigate the latter phenomenon, the authors conducted 3 experiments in which female participants were led to expect a stressful speech task and a confederate peer provided support in such a way that it was either visible or invisible (N=257). Invisible support (practical and emotional) reduced emotional reactivity relative to visible and no support. Visible support was either ineffective or it exacerbated reactivity. Explanatory analyses indicated that support was effective when it avoided communicating a sense of inefficacy to recipients.     

Irrelevant incentive learning during instrumental conditioning: The role of the drive-reinforcer and response-reinforcer relationships

Four experiments investigated the processes by which a motivationally-induced change in the value of the training reinforcer affects instrumental performance. Initially, thirsty rats were trained to lever press for either a sodium or non-sodium solution. In Experiment I sodium-trained rats responded faster in extinction following the induction of a sodium appetite, but not following either food or water deprivation. Thus, enhanced extinction performance depends upon the relevance of the training reinforcer to the test drive state. The remaining experiments examined the role of the instrumental contingency. Animals received response-contingent presentations of one solution alternated either within (Experiments II and III) or between sessions (Experiment IV) with non-contingent presentations of another solution. Neither procedure yielded convincing evidence that contingent sodium presentations generated more responding in extinction under a sodium appetite than did non-contingent sodium presentations. On the basis of these results, we argue that the instrumental contingency itself does not play a major role in this irrelevant incentive effect.     

Predicting and manipulating the incidence of inattentional blindness

Inattentional blindness (IB) occurs when an observer, who is engaged in a resource-consuming task, fails to notice an unexpected although salient stimulus appearing in their visual field. The incidence of IB is affected by changes in stimulus-driven properties, but little research has examined individual differences in IB propensity. We examine working memory capacity (WMC), processing styles (flicker task), inhibition (Stroop task), and training in predicting IB. WMC is associated with IB (Experiments 1 and 2) but neither processing style (Experiment 1) nor inhibition (Experiment 2) was associated. In Experiment 2, prior training on a task reduced the incidence of IB compared to no prior training, and this effect was significantly larger when trained on the same tracking task as that used in the IB task rather than a different task. We conclude that IB is related to WMC and that training can influence the incidence of IB.     

Digitally manipulating memory: Effects of doctored videos and imagination in distorting beliefs and memories

In prior research on false autobiographical beliefs and memories, subjects have been asked to imagine fictional events and have been exposed to false evidence that indicates that the fictional events occurred. But what are the relative contributions of imagination and false evidence toward false belief and memory construction? In the present study, subjects observed and copied various simple actions; then they viewed doctored videos that suggested that they had performed extra actions and they imagined performing some of those and some other actions. Subjects returned 2 weeks later for a memory test. False evidence or imagination alone was often sufficient to cause belief and memory distortions; in combination, they appeared to have additive or even superadditive effects. The results bear on the mechanisms underlying false beliefs and memories, and we propose legal and clinical applications of these findings.     

Hiring bias and the disabled interviewee: Effects of manipulating work history and disability information of the disabled job applicant

Ninety MBA students were randomly assigned to one of six experimental conditions in a 3(levels of disability) × 2(levels of employment history) design. Levels of disability (Physical, Psychiatric, and No Disability) and levels of employment history (Good and Poor) were manipulated by giving the subjects bogus information on a job application form prior to hearing a taped job interview. Subjects then rated the quality of the interview and stated the probability that they would hire the interviewee. Evaluations of the interview and hiring probabilities were different between the experimental groups. Implications and suggestions for future research are discussed.     

Subjective organization and the visibility of illusory contours

The effects of the differential organization of a Necker cube on the perceived salience of an embedded illusory triangle were examined. Overall figural salience was greater when the triangle appeared to be localized on the front rather than the back cube face. Illusory contour salience also increased with increasing inducing area contrast and was greater when the figure was oriented on cardinal as compared to oblique coordinates. However, the latter effects were independent of perceived location within the cube. The finding that subjective organizational and structural factors influenced the perceived salience of the illusory figure but did not interact is consistent with van Tuijl and Leeuwenberg's (1982) suggestion that top-down and bottom-up determinants can operate independently in illusory contour perception.     

Effects of repetitive stress during the acute phase of Trypanosoma cruzi infection on chronic Chagas' disease in rats

The effect of repetitive stress during acute infection with Trypanosoma cruzi (T. cruzi) on the chronic phase of ensuing Chagas' disease was the focus of this investigation. The aim of this study was to evaluate in Wistar rats the influence of repetitive stress during the acute phase of infection (7 days) with the Y strain of T. cruzi on the chronic phase of the infection (at 180 days). Exposure to ether vapor for 1 min twice a day was used as a stressor. Repetitive stress enhanced the number of circulating parasites and cardiac tissue disorganization, from a moderate to a severe diffuse mononuclear inflammatory process and the presence of amastigote burden in the cardiac fibers. Immunological parameters revealed that repetitive stress triggered a reduced concanavalin A induced splenocyte proliferation in vitro with major effects on the late chronic phase. Serum interleukin-12 concentration decreased in both stressed and infected rats in the early phase of infection although it was higher on 180 days post-infection. These results suggest that repetitive stress can markedly impair the host's immune system and enhance the pathological process during the chronic phase of Chagas' disease.     

Peripheral pain enhances the effects of incentive downshifts

Physical pain (induced by tissue damage) and psychological pain (induced by surprising incentive loss) share a set of common neural substrates, but little is known about their interactions. The present research studied such interactions using the formalin test to induce physical pain and consummatory successive negative contrast (cSNC) to induce psychological pain. In the formalin test, animals receive an intradermal injection of formalin (1%) in a hind paw. In cSNC, rats with free access to 32% sucrose show a sharp suppression of drinking behavior after a downshift to 4% sucrose, compared to rats that always receive 4% sucrose. In Experiment 1, formalin administration before the first and second 32-to-4% sucrose downshift trials enhanced cSNC. In Experiment 2, a similar treatment before the first downshift trial after a 16-to-4% sucrose downshift, which normally produces little or no evidence of cSNC, significantly increased cSNC. In Experiment 3, using a 32-to-4% sucrose downshift procedure similar to that of Experiment 1, no effects were observed following formalin administration immediately after Trial 11. Thus, no evidence was found that the effects of physical pain on cSNC were caused by changes in memory consolidation. The procedures used in these experiments offer a new approach to study the neural substrates of interactions between physical and psychological pain.