Unconditional Incentives Research Articles

The Effect of Incentives on Response Rates and Panel Attrition: Results of a Controlled Experiment

Steadily declining response rates lead to an increased usage of incentives in all kind of surveys. As for mail surveys, much empirical evidence supporting the usage of unconditional incentives is available (Berk, Mathiowetz, Ward and White 1987; Church 1993). For face-to-face studies, however, fewer results are available, and even less often in experimental settings (Martin, Abreu and Winters 2001; Singer, Hoewyk, Gebler, Raghunathan and McGonagle 1999). We conducted a three wave panel CAPI survey (N=600), where respondents were randomly assigned to three experimental groups: the first group received an unconditional incentive in form of a 10 Euro voucher, the second group was promised a 10 Euro voucher conditional upon participation, the third group was a control group that received no incentive. The allocation to a given experimental group was constant across the three waves and interviewers were kept blind to the experimental conditions. This research adds to the methodological literature in several ways: firstly, we compared the effectiveness of prepaid and conditional monetary incentives in a face-to-face interview in cross-sectional and longitudinal perspective, and found that conditional incentives performed significantly better in retaining respondents till the third wave. Secondly, we controlled for accurateness of the interviewers’ work on the field, and found evidence that improving selection and training of interviewers remains mandatory, since poor quality in the interviewer pool cannot be compensated by incentives.

Effect of Incentives and Mailing Features on Online Health Program Enrollment

With the growing use of Internet-based interventions, strategies are needed to encourage broader participation. This study examined the effects of combinations of monetary incentives and mailing characteristics on enrollment, retention, and cost effectiveness for an online health program. In 2004, a recruitment letter was mailed to randomly selected Midwestern integrated health system members aged 21-65 and stratified by gender and race/ethnicity; recipients were randomly pre-assigned to one of 24 combinations of incentives and various mailing characteristics. Enrollment and 3-month retention rates were measured by completion of online surveys. Analysis, completed in 2005, compared enrollment and retention factors using t tests and chi-square tests. Multivariate logistic regression modeling assessed the probability of enrollment and retention. Of 12,289 subjects, 531 (4.3%) enrolled online, ranging from 1% to 11% by incentive combination. Highest enrollment occurred with unconditional incentives, and responses varied by gender. Retention rates ranged from 0% to 100%, with highest retention linked to higher-value incentives. The combination of a $2 bill prepaid incentive and the promise of $20 for retention (10% enrollment and 71% retention) was optimal, considering per-subject recruitment costs ($32 enrollment, $70 retention) and equivalent enrollment by gender and race/ethnicity. Cash incentives improved enrollment in an online health program. Men and women responded differently to mailing characteristics and incentives. Including a small prepaid monetary incentive ($2 or $5) and revealing the higher promised-retention incentive was cost effective and boosted enrollment.

Combining conditional and unconditional recruitment incentives could facilitate telephone tracing in surveys of postpartum women

Background and Objective To compare tracing and contact rates using alternative incentives in a computer-assisted telephone interview (CATI) survey among postpartum women. Methods In a randomized trial of 1,061 postpartum women 18–49 years of age selected from four Iowa counties, we compared the effects of: (1) unconditional $5 telephone card incentive enclosed with the introductory letter followed by $25 incentive conditional upon successful telephone tracing, contact, and completion of CATI (Group 1, n = 530) vs. (2) $30 incentive conditional upon subject completion of CATI (Group 2, n = 531). Results Overall telephone tracing and contact rates achieved were 67.8% and 66.6%, respectively. Tracing (70.2 vs. 65.4%, P = .09) and contact (68.5 vs. 64.8%, P = .26) rates were consistently higher among subjects assigned the combination of a conditional and an unconditional incentive. The combined incentive type had a greater impact on telephone tracing success rates for subjects on whom we could not initially locate an active telephone number (16.7 vs. 7.3%, P = .07) when compared to subjects for whom we found an active telephone number at the time of mailing the introductory letter (78.9 vs. 75.9%, P = .30). Conclusions Combining conditional and unconditional recruitment incentives can facilitate telephone tracing efforts in surveys conducted among recently postpartum women.

The adrenergic α 2 receptor and sexual incentive motivation in male rats

The purpose of the present series of experiments was to determine whether drugs acting at the α 2-adrenoceptor modify unconditioned sexual incentive motivation in the male rat. To that end a highly specific agonist, dexmedetomidine, a corresponding antagonist, atipamezole, and a less specific antagonist, yohimbine, were administered to groups of sexually inexperienced male rats. The subjects were tested in a large rectangular arena, where a sexually receptive female and an intact male were employed as incentives. The incentive animals were confined behind a wire mesh in opposite corners of the arena. The animals could see, hear and smell each other, but no sexual interaction was possible. Approach to the incentives constituted the measure of incentive motivation. In addition, the test provided data on ambulatory activity and general arousal. Dexmedetomidine, at a dose of 8 μg/kg, produced a slight reduction of sexual incentive motivation. Ambulatory activity and general arousal were also inhibited. Atipamezole, in doses of 0.1 and 0.3 mg/kg enhanced the positive incentive properties of the receptive female. A high dose of 1 mg/kg did not have any significant effect. Ambulatory activity was slightly reduced by the two larger doses of atipamezole. Yohimbine had a slight stimulatory effect on sexual incentive motivation at a dose (4 mg/kg) that also reduced ambulatory activity and general arousal. It is concluded that blockade of the adrenergic α 2 receptor stimulates sexual incentive motivation in the male rat whereas stimulation of it has the opposite effect. At present it is not clear if these drug effects are caused by pre- or postsynaptic actions of the drugs, and the importance of secondary changes in other neurotransmitter systems remains unknown.

Response Rates to a Mailed Survey Targeting Childhood Cancer Survivors: A Comparison of Conditional versus Unconditional Incentives

Mailed surveys are widely used to collect epidemiologic and health service data. Given that nonresponse can threaten the validity of surveys, modest incentives are often used to increase response rates. A study was undertaken among childhood cancer survivors and their parents to determine if response rate to a mailed survey differed with provision of immediate versus delayed incentives. A self-administered survey designed to ascertain health behaviors was mailed to 397 childhood cancer survivors (and their parents if the survivor was <18 years of age). Subjects were randomized into two groups based on gender, age, race, and cancer type. One group received a 10 US dollars incentive with their blank survey (unconditional incentive), whereas the other group received the incentive upon receipt of their completed survey (conditional incentive). If children were minors, both the parent and the child received incentives. No significant differences in response rates were observed with respect to gender, age, race, or cancer type. However, significant differences in response rates were observed between incentive groups, with unconditional incentives yielding significantly higher response rates than conditional incentives for child survivors who were > or =18 years (64.4% versus 49.0%), as well as younger child survivors (62.5% versus 43.6%) and their parents (64.8% versus 41.5%; all P < 0.05). The provision of an immediate incentive generated significantly higher response rates to this mailed health survey among childhood cancer survivors and their parents. Given that survey studies are commonly conducted across various pediatric populations, these findings may help inform the design of future pediatric survey research.

Contingent versus unconditional incentives in WWW-studies

Five experiments examined how participation in WWW-studies was influenced by framing the reception of an incentive as contingent on the completeness of the submitted questionnaire. Four experiments were carried out in a university-based online panel and one in a market research online panel. Four times the incentive was a prize draw and once it was a personal gift. In each experiment, two conditions were contrasted: one group received an e-mail invitation mentioning that all participants are eligible for the incentive (= unconditional incentive), whereas the other group was told that only those participants who answer every question in the questionnaire would receive the incentive (= contingent incentive). Dependent measures were response rate, retention rate, number of omitted closed-ended items, length of answers to open-ended questions, and stereotypical answering of grid-like question batteries. There were no significant effects. The results of the individual experiments were then meta-analytically aggregated. It was revealed that contingent relative to unconditional incentives decrease response to a study, while at the same time the sparser data are not compensated for by a superior data quality or retention.

No Difference in Response Rate to a Mailed Survey among Prostate Cancer Survivors Using Conditional versus Unconditional Incentives

Mailed surveys are widely used to collect epidemiological and health service data on cancer populations. Nonresponse can threaten the validity of surveys and various strategies, including the enclosure of modest incentives, are often used to increase response rates. A study was undertaken to determine whether response rate to a mailed survey differed with provision of immediate versus delayed incentives. A six-page mailed survey to ascertain dietary supplement use was sent to 1402 men who had been diagnosed with prostate cancer. Subjects were block randomized into two groups based on age (< or =65 years versus >65 years), race (white versus nonwhite), and disease status (locoregional versus distant). One group received a 30-min prepaid phone card concurrently with their blank survey (unconditional incentive), whereas the other group received the incentive only on receipt of their completed survey (conditional incentive). A 60% overall response rate was achieved, and no differences in response rates were noted between conditional and unconditional incentive groups (overall, as well as within defined age, race, and disease-defined strata). Nonwhites, however, were significantly less likely to respond than whites (P < 0.0001). In conclusion, acceptable response rates to a mailed survey can be achieved in a general population of cancer survivors using modest incentives. Given no differences in response rates using conditional versus unconditional incentives, the decision to provide immediate versus delayed incentives is one that should be considered on a study-specific basis, and a decision based primarily on cost. Other means, however, appear necessary to achieve acceptable response rates among minority group cancer survivors.

Lack of opioid or dopaminergic effects on unconditioned sexual incentive motivation in male rats.

Lack of opioid or dopaminergic effects on unconditioned sexual incentive motivation in male rats.

Lack of opioid or dopaminergic effects on unconditioned sexual incentive motivation in male rats.

The effects of dopaminergic and opioidergic drugs on sexual incentive motivation were evaluated in sexually inexperienced male rats subjected to a choice procedure. Various parameters of ambulatory activity were recorded as well. Two drugs stimulating dopaminergic neurotransmission, amphetamine and apomorphine, failed to affect sexual incentive motivation, although ambulatory activity was enhanced by amphetamine. The dopamine antagonist cis(Z)-flupenthixol reduced sexual incentive motivation, but only at a dose that severely disrupted motor function. Morphine had marginal effects on sexual motivation but reduced ambulatory activity. These effects were not reduced by a peripheral opioid antagonist, methylnaloxone. Loperamide, a peripheral opioid agonist, reduced sexual motivation through an opioid-independent action. Naloxone was ineffective. Neither dopamine nor opioids seem to be important for sexual incentive motivation.

Dopamine antagonism attenuates the unconditioned incentive value of estrous female cues

The role of dopaminergic transmission in the incentive–motivational processes involved in the generation of male sexual behavior was examined. Three groups of sexually naı̈ve Long–Evans male rats traversed a straight alley for one of three goalbox targets: an empty goalbox, a nonestrous female, or an estrous female. A Plexiglas partition within the goalbox allowed for the perception of visual, auditory, and olfactory cues, but prevented physical contact. Baseline run times revealed that subjects returned to the goalbox significantly faster for an estrous female than for a nonestrous female, replicating our earlier work on the inherent incentive value of primary female cues. When subjects were then pretreated with the dopamine receptor antagonist, haloperidol (0.0, 0.075, or 0.15 mg/kg), they expressed decreased sexual motivation as reflected by increased run times for estrous female targets. Subjects' run times for the empty goalbox condition were unaffected by haloperidol, suggesting that the drug did not reliably impair motoric capacity. Results support the contention that central dopaminergic systems are involved in the regulation of the positive, unconditioned incentive value of estrous female cues.

Animal models of drug craving.

Drug craving, the desire to experience the effect(s) of a previously experienced psychoactive substance, has been hypothesized to contribute significantly to continued drug use and relapse after a period of abstinence in humans. In more theoretical terms, drug craving can be conceptualized within the framework of incentive motivational theories of behavior and be defined as the incentive motivation to self-administer a psychoactive substance. The incentive-motivational value of drugs is hypothesized to be determined by a continuous interaction between the hedonic rewarding properties of drugs (incentive) and the motivational state of the organism (organismic state). In drug-dependent individuals, the incentive-motivational value of drugs (i.e., drug craving) is greater compared to non-drug-dependent individuals due to the motivational state (i.e., withdrawal) developed with repeated drug administration. In this conceptual framework, animal models of drug craving would reflect two aspects of the incentive motivation to self-administer a psychoactive substance. One aspect would be the unconditioned incentive (reinforcing) value of the drug itself. The other aspect would be relatively independent of the direct (unconditioned) incentive value of the drug itself and could be reflected in the ability of previously neutral stimuli to acquire conditioned incentive properties that could elicit drug-seeking and drug-taking behavior. Animal models of drug craving that permit the investigation of the behavioral and neurobiological components of these two aspects of drug craving are reviewed and evaluated. The models reviewed are the progressive ratio, choice, extinction, conditioned reinforcement and second-order schedule paradigms. These animal models are evaluated according to two criteria that are established herein as necessary and sufficient criteria for the evaluation of animal models of human psychopathology: reliability and predictive validity. The development of animal models of drug craving will have heuristic value and allow a systematic investigation of the neurobiological mechanisms of craving.

Associative regulation of Pavlovian fear conditioning: Unconditioned stimulus intensity, incentive shifts, and latent inhibition.

Associative regulation of Pavlovian fear conditioning: Unconditioned stimulus intensity, incentive shifts, and latent inhibition.

Associative regulation of Pavlovian fear conditioning: unconditional stimulus intensity, incentive shifts, and latent inhibition.

Conditional stimuli (CS) associated with painful unconditional stimuli (US) produce a naloxone-reversible analgesia. The analgesia serves as a negative-feedback regulation of fear conditioning that can account for the impact of US intensity and CS predictiveness on Pavlovian fear conditioning. In Experiment 1 training under naloxone produced learning curves that approached the same high asymptote despite US intensity. Shifting drug treatment during acquisition had effects that paralleled US intensity shifts. In Experiment 3 naloxone reversed Hall-Pearce (1979) negative transfer using a contextual CS, indicating that conditional analgesia acquired during the CS-weak-footshock phase retards acquisition in the CS-strong-footshock phase. Experiment 5 used a tone CS in both a latent-inhibition and a negative-transfer procedure. Only negative transfer was blocked by naloxone. Therefore, negative transfer but not latent inhibition is mediated by a reduction of US processing.