Duration sensitivity depends on stimulus familiarity.

When people are asked to assess or compare the value of experienced or hypothetical events, one of the most intriguing observations is their apparent insensitivity to event duration. The authors propose that duration insensitivity occurs when stimuli are evaluated in isolation because they typically lack comparison information. People should be able to evaluate the duration of stimuli in isolation, however, when stimuli are familiar and evoke comparison information. The results of 3 experiments support the hypothesis. Participants were insensitive to the duration of hypothetical (Experiment 1) and real (Experiment 2) unfamiliar experiences but sensitive to the duration of familiar experiences. In Experiment 3, participants were insensitive to the duration of an unfamiliar noise when it was unlabeled but sensitive to its duration when it was given a familiar label (i.e., a telephone ring). Rather than being a unique phenomenon, duration neglect (and perhaps other forms of scope insensitivity) appears to be a particular case of insensitivity to unfamiliar attributes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phenomenology depends on human nature.

Comments on the article "Psychology and Phenomenology: A Clarification" by H. H. Kendler (see record 2005-05480-003). Kendler contrasted objective phenomena going on in the mind with phenomenological convictions. He concluded, on the basis of a thoughtful analysis, that scientific psychology cannot validate moral principles, which have to be agreed upon by discussion among educated members of a democratic community. He recommended psychological research on the consequences of social policies that may facilitate humans' decisions. I argue that research on the nature of phenomenological convictions is useful as well, enabling human beings to amend their strategies when reasoning about moral values. Scientific psychology can contribute to moral reasoning not only by examining social consequences of certain policies but also by highlighting the very process, starting from phenomenological convictions and ending in moral values within a community. Thus, psychological research contributes to the reflection of how members of a community exert their freedom and may give them the opportunity to enhance their reasoning and negotiation procedures. Scholars have to be humble and admit that the limit to this enhancement lies in the limitations of human reasoning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic influences on latent inhibition.

The present study examined the development of latent inhibition in a number of inbred strains of mice. C57BL/6J, DBA/2J, C3H/Ibg, BALB/cByJ, A/J, CBA/J, 129/SvevTac, 129/SvJ, and AKR/J mice were screened for the development of latent inhibition. The latent inhibition paradigm involved 1 day of either 40 preexposures to the conditioned stimulus (CS) or no preexposure. On the following training day, the CS was twice paired with a shock unconditioned stimulus (US). On a subsequent test day, the strength of the CS—US association was measured. Mice preexposed to the CS should show a weaker CS—US association, which would reflect development of latent inhibition. Significant between-strain differences existed. The 129/Svev, C57BL/6, BALB/cByJ, AKR, and DBA/2 mice developed latent inhibition, but 129/SvJ, CBA, A, and C3H mice did not. Thus, genetic variance contributes to variability in the development of latent inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potentiation of latent inhibition.

Rats were given exposure either to an odor (almond) or a compound of odor plus taste (almond plus saline), prior to training in which the odor served as the conditioned stimulus. It was found, for both appetitive and aversive procedures, that conditioning was retarded by preexposure (a latent inhibition effect), and the extent of the retardation was greater in rats preexposed to the compound (i.e., latent inhibition to the odor was potentiated by the presence of the taste). In contrast, the presence of the taste during conditioning itself overshadowed learning about the odor. We argue that the presence of the salient taste in compound with the odor enhances the rate of associative learning, producing a rapid loss in the associability of the odor. This loss of associability will generate both overshadowing and the potentiation of latent inhibition that is observed after preexposure to the compound. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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

Conditional stimuli (CS) associated with painful unconditional stimuli (UCS) produce a naloxone-reversible analgesia. The analgesia serves as a negative-feedback regulation of fear conditioning that can account for the impact of UCS intensity and CS predictiveness on Pavlovian fear conditioning. In Exp 1, training under naloxone produced learning curves that approached the same high asymptote despite UCS intensity. Shifting drug treatment during acquisition had effects that paralleled UCS intensity shifts. In Exp 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. Exp 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 UCS processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When pentobarbital is the conditioned stimulus and amphetamine is the unconditioned stimulus, conditioning depends on the type of conditioned response.

Injections of drugs into rats were used as conditioned stimuli (CSs) and as unconditioned stimuli (UCSs). With heart rate (HR) conditioning, the pentobarbital CS produces a higher HR than under control conditions. With avfail (aversion failure) conditioning, the pentobarbital CS loses much of its capacity to induce a conditioned taste aversion. HR conditioning was obtained with forward delays of up to 30 min and backward delays of up to 270 min, where the delays are defined by the interinjection interval. Avfail was obtained with forward delays of up to 270 min but not with backward delays. Neither HR conditioning nor avfail were context specific but could be demonstrated in a test apparatus after pairings that occurred in the home cage. This indicated that the external environment was not an important part of the effective stimulus complex. When HR conditioning was obtained, its latency and duration was not related to the delay between the CS and UCS injections or whether they were forward or backward. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Responding to a conditioned stimulus depends on the current associative status of other cues present during training of that specific stimulus.

The comparator hypothesis is a response rule stating that responding to a Pavlovian conditioned stimulus/stimuli (CS) reflects the associative strength of the CS relative to that of other cues (comparator stimuli) that were present during CS training. Thus, modulation of the associative strength of a CS's comparator stimulus should alter responding to that CS. These studies examined the stimulus specificity of this effect using within-Ss designs. Rats were trained on 2 CSs, each with a unique comparator stimulus, to determine the degree to which posttraining extinction of the comparator stimulus for one CS influences responding to the other CS. Using negative contingency (Exps 1 and 2), overshadowing (Exp 3), and local context (Exp 4) preparations, stimulus specificity was observed. In each case, posttraining extinction of the comparator stimulus for one CS had greater impact on responding to that CS than on responding to the alternate CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stroop dilution depends on the nature of the color carrier but not on its location.

Stroop dilution is the reduction of the Stroop effect in the presence of a neutral word. It has been attributed to competition for attention between the color word and neutral word, to competition between all stimuli in the visual field, and to perceptual interference. Five experiments tested these accounts. The critical manipulation was whether the color to be named was carried by the color word or the neutral word. Neutral words diluted the Stroop effect when they were the color carrier, but not when the color word was the color carrier. We argue that Stroop dilution is due to attentional competition between the color word and neutral word, with priority given to the color carrier. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Conditioned stimulus control in the rat circadian system depends on clock resetting during conditioning.

The authors examined the ability of a conditioned stimulus (CS; mild air disturbance) previously paired with an entraining light pulse to reset the circadian pacemaker in rats. Rats were entrained to a single 30-min light stimulus delivered every 25 hr or 24 hr (T cycle). Each daily light presentation was paired with the CS. After at least 20 days of stable entrainment to each of the T cycles, the rats were allowed to free run and were then presented with the CS at circadian time 15. CS-induced phase shifts in wheel-running activity rhythms were taken as evidence for conditioning. For the most part, conditioning occurred after CS-light pairings on the 25-hr but not 24-hr T cycle. The results suggest that CS control of the circadian clock phase depends on the effect that the entraining light pulse has on the clock during conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blocking of potentiation of latent inhibition.

We present a theory of latent inhibition based on the Pearce–Hall (Pearce & Hall, 1980) model for classical conditioning. Its central features are (1) that the associability of a stimulus declines as it comes to predict its consequences and (2) that nonreinforced exposure to a stimulus engages an associative learning process that makes the stimulus an accurate predictor of its consequences (in this case, the occurrence of no event). A formalization of this theory is shown to accommodate the finding that preexposure in compound with another cue can potentiate latent inhibition to the target cue. It further predicts that preexposure to the added cue will eliminate the potentiation effect. An experiment using rats and the flavor-aversion procedure confirmed this prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Novel factors contributing to the expression of latent inhibition.

Behavioral and neural correlates of latent inhibition (LI) during eyeblink conditioning were studied in 2 experiments. In Experiment 1, rabbits (Oryctolagus cuniculus) were conditioned after 8 days of tone conditioned stimulus (CS) presentations or 8 days of context-alone experience. LI was seen in the CS-preexposed rabbits when a relatively intense (5 psi) airpuff unconditioned stimulus was paired with the CS. In Experiment 2, rabbits were given 0, 4, or 8 days of CS preexposures or context-alone experience. Hippocampal activity was monitored from the 8-day CS- or context-exposure rabbits. The LI effect was seen only in rabbits given 4 days of CS preexposure, thus suggesting that LI depended largely on the rate of acquisition in the context-preexposed control group. The neural recordings showed that the hippocampus was sensitive to the relative novelty of the stimuli and the overall context, regardless of whether exposure to stimuli and context promoted LI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the nature of the conditioned stimulus: Comment on Leri and Stewart (2002).

F. Leri and J. Stewart (see record 2002-06535-001) present convincing evidence that a relapse to heroin-seeking behavior is established when rats are given a momentary lapse in which they are allowed to respond while under the influence of heroin. Although exposure to a conditioned stimulus (CS) paired with heroin self-infusion did not induce a relapse, it was able to control responding. In addition to serving as both a discriminative stimulus and a conditioned reinforcer, it is argued in this article that the CS also may have positive hedonic value independent of its association with heroin and that this property should be considered in interpreting the results of future experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of nicotine and amphetamine on latent inhibition in human subjects

The final color of all-ceramic restorations is dependent on the surrounding structures and on the ceramic itself. The degree that the layer of the composite luting agent contributes to this final color formation can only be estimated. Based on general optical physics, this paper reports on transmissivity of some commercially available composite luting resins and discusses how these theoretical results apply to clinical situations.     

Cingulate cortical coding of context-dependent latent inhibition.

Neuronal activity of the auditory thalamus, amygdala, cingulate cortex, and substantia nigra was recorded during the administration of a behavioral test for latent inhibition (LI) or the retardation of behavioral conditioning because of preexposure of the conditional stimulus (CS). Following CS preexposure, both the preexposed CS and a control CS predicted avoidable footshock. LI occurred as significantly fewer avoidance conditioned avoidance responses after the preexposed CS than after the control CS. Attenuation of neuronal responses to the preexposed CS, or neural LI, occurred in all monitored areas. One group of subjects (Oryctolagus cuniculus) then received context extinction, and additional groups experienced novel context exposure or handling. Context extinction enhanced behavioral responding to the preexposed CS, eliminating LI. Context extinction also eliminated cingulate cortical neural LI by enhancing posterior cingulate cortical responses to the preexposed CS and attenuating anterior cingulate cortical responses to the control CS. Present and past results are interpreted to indicate that LI is (a) a failure of response retrieval and/or expression mediated by interfering CS-context associations and (b) a product of interactions of the posterior cingulate cortex and the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The loss of latent inhibition across compound conditioning.

Six experiments used a magazine approach paradigm with rats to investigate latent inhibition (LI). Experiment 1 found that compound conditioning did not increase evidence for LI, in contrast to predictions from acquisition-deficit models that are based on a common error term (e.g., J. M. Pearce & G. Hall, 1980; A. R. Wagner, 1981). Instead, it appeared that preexposed and non-preexposed stimuli conditioned to the same asymptote following compound conditioning, as is the case when these stimuli are conditioned separately. This was confirmed in three further experiments that used probe trials to measure conditioning to each conditioned stimulus across the course of compound training. In these experiments, LI was observed during initial but not extended compound training, consistent with predictions derived from M. E. Bouton (1997) and the SLG model (N. A. Schmajuk, Y. Lam, & J. A. Gray, 1996). However, 2 further experiments did not support these models. Instead, these findings are most consistent with models that use separate error terms to compute the associative strength of conditioned stimuli conditioned in compound (S. E. Brandon, E. H. Vogel, & A. R. Wagner, 2003; M. E. Le Pelley, 2004; N. J. Mackintosh, 1975). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term effects of repeated maternal separation on three different latent inhibition paradigms

In the present study we investigated the effect of repeated maternal separation on postnatal days 12, 14, 16, and 18 for 6 h/day on Wistar rats on three latent inhibition (LI) paradigms: two-way active avoidance, conditioned emotional response (CER), and conditioned taste aversion (CTA). In addition, hyperactivity induced by d-amphetamine and stereotypies induced by apomorphine were evaluated. In all three LI experiments, the control animals showed only marginal LI, whereas the maternally separated animals showed enhanced LI (only males in CTA). In two-way active avoidance within the nonpreexposed condition maternally separated animals showed improved acquisition of avoidance learning compared with the control animals. Sensitivity in response to amphetamine and apomorphine was not altered by the maternal separation procedure. Thus, maternal separation in this study, contrary to previous reports, but in line with results obtained following early handling before weaning, led to enhancement of the LI phenomenon as assessed in each of the three procedures. As our maternal separation procedure (6 h on days 12, 14, 16, and 18) led to behavioral outcomes that differed from those reported by Ellenbroek and Cools (24 h on day 10), it is suggested that maternal separation regimens that are dissimilar may lead to different and sometimes opposite behavioral effects.     

Some theoretical considerations on the nature of ambiguity and the use of stimulus dimensions in projective techniques.

Attention is drawn to some common misconceptions about ambiguous stimuli and to some of the advantages and limitations associated with the use of structured stimuli. It is noted that the use of stimulus dimensions allows for the retention of the positive features of both kinds of stimuli, while yielding additional information from their interaction. Suggestions for further research are presented, with emphasis upon the measurement of conflict via stimulus dimensions and 3 response correlates, i.e., selective verbal content, physiological activation, and performance deficit. (30 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some tests of the strategy disruption interpretation of part-list cuing inhibition.

Part-list cuing inhibition is diminished recall for the remainder of a studied list when part of that list is provided on the recall test. In Experiments 1–3, participants formed arbitrary subcategories. Inhibition was absent when cues were consistent with those subcategories but present when cues were inconsistent with them. In Experiment 4, participants failed to adapt to part-list cuing, despite its presence on several training trials. In Experiment 5, a subcategorical retrieval strategy consistent with the presence of cues effectively eliminated inhibition whether that strategy was suggested at study or at recall. Two findings indicated that part-list cuing may be inconsistent with some retrieval strategies that produce recall segregated by subcategory. Most findings supported the strategy disruption position that inhibition results when a whole-list retrieval strategy is abandoned for a less effective part-list retrieval strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhancement of latent inhibition in the rat by the atypical antipsychotic agent remoxipride

It has been hypothesized that as large arteries become more rigid with age, the pattern of hypertension changes from diastolic to systolic. Thus, diastolic blood pressure (DBP) may lose its ability to reflect the increase in vascular resistance with age. To assess this, we studied the age-related changes in blood pressure pattern and its steady-state and pulsatile determinants. We performed an epidemiological analysis based on a national survey of 10,462 subjects from Argentina. A hemodynamic analysis (impedance cardiography) was then carried out in 636 consecutive hypertensive patients (age, 25 to 74 years). Whereas the rate of increment in the prevalence of mild to moderate hypertension (MMH) reached a plateau after the sixth decade, isolated and borderline systolic forms of hypertension began a steep and sustained rise. Among patients with MMH, DBP remained stable from the third to the seventh decade, whereas SBP maintained a sustained increase. Despite similar DBP, the systemic vascular resistance index increased 47% (P<.01) and the cardiac index decreased 27% (P<.01), whereas the ratio of stroke volume to pulse pressure, an index of arterial compliance, decreased 45% (P<.01). However, there were no significant differences between older patients with MMH and those with isolated systolic hypertension in the level of SBP, vascular resistance, stroke volume, and cardiac index. Compared with age-matched normotensive control subjects, the ratio of stroke volume to pulse pressure was much more reduced in isolated systolic hypertension (48%) than in MMH (30%). In summary, the present study, carried out in a large sample of hypertensive subjects with a wide age range, showed a simultaneous impairment in vascular resistance and arterial compliance associated with aging in different patterns of hypertension. The magnitude of these changes, with opposite effects on DBP but additive effects on SBP, suggests that a hemodynamic mechanism could determine the transition in the prevalence of diastolic hypertension toward a systolic pattern of hypertension with aging. Also, the results suggest that SBP, but not DBP, is a reliable indicator of the underlying hemodynamic abnormalities (high resistance and low arterial compliance) in the elderly.