Perception of less irregular and more irregular stimuli.

Berlyne's stimuli were presented in a stereoscope to test his hypothesis that Ss prefer the more irregular member of a pair of stimuli. 32 Ss, screened for normal acuity and phorias, were tested. Contrary to Berlyne's hypothesis and consistent with earlier stereoscopic studies, Ss tend to report more frequently the less irregular member of a pair of stimuli. These data can be explained by an information-conflict model; however, the clearest implication of this study was that experiments concerned with familiarity of stimuli should be qualified by the method.     

The Fluency Amplification Model: Fluent stimuli show more intense but not evidently more positive evaluations

Processing fluency plays a large role in forming judgments, as research repeatedly shows. According to the Hedonic Fluency Model, more fluently processed stimuli are rated more affectively positive than less fluently processed stimuli. Most research documenting such findings uses neutral or positive stimuli with low complexity, thus any potential impact of initial stimulus valence cannot be tested. In the present study, 60 IAPS stimuli ranging from very negative to very positive valence were rated on liking by participants. Processing fluency was manipulated through perceptual priming (7 ms). Results of Experiment 1 (N = 35) support the prediction of the Hedonic Fluency Model, but only for stimuli with an initially positive valence. However, when negative stimuli were processed more fluently, they were rated as more negative than when processed less fluently. Experiment 2 (N = 39) showed that enhancing the accessibility of the stimulus content (via prolonging the prime duration to 100 ms) cannot account for the results of Experiment 1, since Experiment 2 failed to replicate the findings obtained in Experiment 1. Potential factors influencing affective evaluation of negative stimuli are discussed. A model is offered for the reinterpretation of processing fluency as an amplifying factor for evaluative judgment.     

Depressed people are not less motivated by personal goals but are more pessimistic about attaining them

Despite its theoretical importance, personal goal motivation has rarely been examined in clinical depression. Here we investigate whether clinically depressed persons (n = 23) differ from never-depressed persons (n = 26) on number of freely generated approach and avoidance goals, appraisals of these goals, and reasons why these goals would and would not be achieved. Participants listed approach and avoidance goals separately and generated explanations for why they would (pro) and would not (con) achieve their most important approach and avoidance goals, before rating the importance, likelihood, and perceived control of goal outcomes. Counter to hypothesis, depressed persons did not differ from never-depressed controls on number of approach or avoidance goals, or on the perceived importance of these goals. However, compared to never-depressed controls, depressed individuals gave lower likelihood judgments for desirable approach goal outcomes, tended to give higher likelihood judgments for undesirable to-be-avoided goal outcomes, and gave lower ratings of their control over goal outcomes. Furthermore, although controls generated significantly more pro than con reasons for goal achievement, depressed participants did not. These results suggest that depressed persons do not lack valued goals but are more pessimistic about their likelihood, controllability, and reasons for successful goal attainment.     

Blocking but not conditioned inhibition results when an added stimulus is reinforced in compound with multiple pretrained stimuli

Conditioned barpress suppression by rats was used to explore the associative status of an initially neutral stimulus that was reinforced in simultaneous compound with two independently pretrained conditioned excitors. In contrast to the Rescorla-Wagner model, which predicts that the target stimulus (X) will be inhibitory following such A+/B+/ABX+ training, the present study found no evidence that X acquired inhibitory associative strength. Rather, the pretrained stimuli merely served to block conditioned excitatory responding to the target stimulus.     

"Like an uncle but more, but less than a father"-Irish children's relationships with nonresident fathers

Although previous research has highlighted the importance of the quality of nonresident father-child relationships for children's well-being, little is known about children's perspectives on what underpins feelings of closeness to their nonresident fathers. This qualitative study explored the processes that facilitate or constrain children's feelings of closeness to their nonresident fathers. Semistructured interviews were conducted with 27 children (ages 8 to 17) who had grown up in a single-mother household, where fathers were nonresident from early in the child's life. Findings revealed the fragility of children's ties with their nonresident fathers and the risk that nonresidence from the outset placed upon these relationships. Children's experiences of closeness to fathers were related to perceptions of their fathers' commitment to their relationship and his obligation to his parenting role, and to a sense of connection to and familiarity with their fathers. It was a challenge for children to feel connected to their fathers when contact arrangements were detached from caregiving activities and precluded immersion in each other's daily lives. Lack of effort on the part of fathers to maintain contact or failure to keep arrangements constrained children's feelings of closeness and gave rise to feelings of disappointment and anger. Children demonstrated their capacity to act as agents within their families as they made sense of these relationships for themselves and accepted or rejected their father as a person who could play a meaningful role in their lives. The implications of the findings for promoting positive relationships with nonresident fathers are discussed.     

An increase in stimulus arousal has differential effects on the processing speed of pleasant and unpleasant stimuli

The arousal value of a stimulus influences its salience, whereby higher arousal should lead to faster processing. However, in previous research, participants consistently made faster valence judgments for low arousal, pleasant stimuli than for high arousal, pleasant stimuli. The speed of valence and arousal judgments for pictures and words were investigated in three experiments. Valence judgments were faster for low arousal than for high arousal pleasant pictures and for high arousal than for low arousal unpleasant pictures and words. Moreover, arousal judgments were faster for low arousal than high arousal pleasant and for high arousal than low arousal unpleasant pictures and words. The current research confirms that the impact of valence and arousal on processing speed does not reflect on the labels (valence versus arousal) used when recording speeded judgments. Similarly to valence, stimulus arousal interacts differentially with the evaluation of pleasant and unpleasant stimuli producing a processing advantage for high arousal, unpleasant stimuli but not high arousal, pleasant stimuli.     

Many stimuli are frightening,but some are more frightening than others: The contributions of preparedness,dangerousness, and unpredictability to making a stimulus fearful

The nonrandom distribution of situational fears has been explained by evolutionary survival relevance of specific fears. Thirty-eight stimuli were taken from the literature on preparedness and were scored on fearfulness, objective dangerousness, and spatiotemporal unpredictability by three separate groups of students. The same items were scored on survival relevance by 15 biologists. Fearfulness of cues significantly correlated not only with survival relevance but also, and even more strongly, with dangerousness and unpredictability. While the fear/survival relevance association virtually disappeared when the unpredictability contribution was partialed out, the fear/unpredictability correlation was only marginally affected when controlling for survival relevance. This suggests that nonrandomness of feared stimuli may result from the spatiotemporal unpredictability that is attributed to these stimuli. The current practice of using snakes and spiders as phobia-relevant, and flowers and mushrooms as neutral, cues was not justified by the ratings of the 15 independent experts.This study was supported in part by a grant from the Dutch Organization for Fundamental Research (ZWO/Psychon, 560-268-001).     

An action sequence held in memory can interfere with response selection of a target stimulus,but does not interfere with response activation of noise stimuli

Withholding an action plan in memory for later execution can delay execution of another action if the actions share a similar (compatible) action feature (e.g., response hand). We investigated whether this phenomenon, termed compatibility interference (CI), occurs for responses associated with a target as well as responses associated with distractors in a visual selection task. Participants planned and withheld a sequence of keypress responses (with their right or left hand), according to the identity of a stimulus (A), and then immediately executed a keypress response (with their right or left hand) to a second stimulus (B), according to the identity of a target letter appearing alone or among distractor letters. Distractor letters were either response compatible or incompatible with the target and appeared either simultaneously with the target (Experiments 1A and 2) or 100 msec before the target (Experiment 1B). Also, stimulus-response mapping was either 1:1 (Experiment 1) or 2:1 (Experiment 2). Results showed that the response to the Stimulus B target was delayed when it required the same response hand as Stimulus A, as opposed to a different hand. Also, the target reaction time for Stimulus B was greater when the target was flanked by incompatible distractors than when it was flanked by compatible distractors. Moreover, the degree of CI was consistent across the compatible-, incompatible-, and no-distractor conditions, indicating that CI generalizes to responses associated with a target, but not to those associated with distractors. Thus, CI occurs at a response selection, not at a response activation stage. Implications for the code occupation account for CI (e.g., Stoet & Hommel, 1999, 2002) and an alternative account for CI are discussed.     

Paradoxical preference for more frequently occurring negative stimuli and for less frequently occurring positive stimuli as a function of amount of training in simultaneous discrimination learning

Development of a preference for more frequently occurring negative stimuli was found in a within-subject design. In this experiment, pigeons learned two simultaneous problems with an unequal number of training trials. At various stages in training, for example, the more-trained negative stimulus was paired with the less-trained negative stimulus for a single preference trial. These probe trials pointed to a swing in stimulus function in negative stimuli which also occurred at an earlier stage in positive (reward-correlated) stimuli. The paradoxical preference for less-trained positive over more-trained positive stimuli was found in this study, confirming the earlier reported phenomenon. The paradoxical preference for more-trained negative stimuli was discussed in terms of a frustration analysis. A symmetrical, albeit positive, emotional factor was discussed with regard to the paradoxical findings with positive probe trials.     

On the development of more and less

More and less were analyzed into two meaning dimensions, “occurrence” (derived from children's early language) and “quantity,” which were hypothesized to be developmentally related to acts of addition and subtraction. Two experiments tested 2- and 3-yr-old's comprehension of these concepts when initially equal or unequal rows were added to, subtracted from or left static. Addition and subtraction had little effect on Ss′ comprehension of either term. Two-year-old Ss understood more when differences in the number of objects in the array were relatively large, suggesting “many” as an intermediate stage of meaning for more. Three-year-olds understood less first as “smaller in amount,” not as more as others have found. Less was acquired later than more, a difference possibly due to its relatively restricted meaning and use or to its converse perceptual and logical relation to more.     

Compound stimuli in emergent stimulus relations: Extending the scope of stimulus equivalence

Three experiments were conducted to investigate stimulus relations that might emerge when college students are taught relations between compound sample stimuli and unitary comparison stimuli using match-to-sample procedures. In Experiment 1, subjects were taught nine AB-C stimulus relations, then tested for the emergence of 18 AC-B and BC-A relations. All subjects showed the emergence of all tested relations. Twelve subjects participated in Experiment 2. Six subjects were taught nine AB-C relations and were then tested for symmetrical (C-AB) relations. Six subjects were taught nine AB-C and three C-D relations and were then tested for nine AB-D (transitive) relations. Five of 6 subjects demonstrated the emergence of symmetrical relations, and 6 subjects showed the emergence of transitivity. In Experiment 3, 5 college students were taught nine AB-C and three C-D relations and were then tested for nine equivalence (D-AB) relations and 18 AD-B and BD-A relations. Three subjects demonstrated all tested relations. One subject demonstrated the AD-B and BD-A relations but not the D-AB relations. One subject did not respond systematically during testing. The results of these experiments extend stimulus equivalence research to more complex cases.     

Attentional load modulates mislocalization of moving stimuli,but does not eliminate the error

Localization of the onset and offset of a moving target is subject to a number of errors that have to be attributed to events following or preceding the target event. Apparently, observers are unable to ignore the spatiotemporal context surrounding the target event. In two experiments, observers’ attention was directed toward a single position along a trajectory, two positions along a single trajectory, or two positions along two different trajectories. In the latter condition, attention to details of a single trajectory was reduced. At the same time, motion type was manipulated by varying the temporal interval between successive target presentations. The localization error was not affected by attentional load; however, effects of motion type were eliminated when two trajectories had to be attended to. It may be sufficient to notice that the target has moved for localization errors to occur, while specifics of the trajectory are ignored.     

Changes in threshold level produced by a signal preceding or following the threshold stimulus

In a previous experiment (Howarth and Treisman, 1958) it was shown that when a warning preceded a stimulus by a fixed interval, the threshold level for the stimulus was higher the longer the fixed interval. A model of this effect was proposed, assuming that the threshold criterion adopted by the subject at any moment was modified by his estimate of the probability of a stimulus at that moment.

Three predictions are derived and tested. It is found that: the standard deviation of the response is constant despite the shifts in threshold induced; the threshold continues to fall as the interval from warning to stimulus is decreased to zero, with the lowest threshold when the warning signal and the stimulus are simultaneous; and that a warning signal following the stimulus by an interval of less than 0 5 to 1 sec. also lowers the threshold.     

Loss of control by a less valid or by a less salient stimulus compounded with a better predictor of reinforcement

An unsalient stimulus, or one imperfectly correlated with reinforcement, may acquire significant control over responding, provided that it is the only available signal for reinforcement, but may fail to acquire control if it is reinforced only in conjunction with a second, more salient or more valid stimulus. A stimulus imperfectly correlated with reinforcement may also lose control over responding if having initially been reinforced in isolation, it is subsequently reinforced only in conjunction with another, more valid stimulus. If the effects of relative salience are to be explained in exactly the same way as those of relative validity, we should expect a similar loss of control by an unsalient stimulus, A, if, after initial consistently reinforced trials to A alone, subjects subsequently receive reinforcement only in the presence of a compound stimulus, A + B. Two experiments on discrete-trial discrimination learning in pigeons and one on conditioned suppression in rats confirm this expectation. The results have implications for theories of selective association in conditioning and discrimination learning.     

Rats with dorsal hippocampal lesions do react to new stimuli but not to spatial changes of known stimuli

The effect of visual distracting stimuli upon the straight alleyway performance of dorsal hippocampectomized Wistar rats was investigated. In comparison with control animals it was observed that dorsal hippocampectomized animals (1) ambulated more during the preexposure phase, (2) acquired at the same rate a running response for food (training phase), (3) reacted similarly to a new visual stimulus (black cards) presented in a sector of the alleyway, and (4) habituated to successive presentations of that stimulus in the same place. (5) However, dorsal hippocampectomized rats did not react, unlike the controls, to the presentation of the same stimulus in another place of the alleyway but (6) reacted to the visual pattern change of the stimulus (now black/white check cards) in the same place. These results indicate that under certain experimental conditions, hippocampus-lesioned animals are capable of interrupting a running response for food in order to explore a new conspicuously located stimulus, habituate to repeated presentations of that stimulus, and to react to a new pattern of visual stimulation. They suggest that hippocampectomized rats do not lose the capacity to react to a new stimulus; the disruption seems to be related to the spatial context of stimulus presentation, supporting a spatial mapping hypothesis of hippocampal function.     

Language lateralization in bilinguals: more not less is needed: a reply to Paradis (1990).

Paradis (1990) took an extremely pessimistic view of research to date looking at the lateralization of cerebral function in bilingual subjects. We, however, argue that some of his conclusions are, in fact, incorrect, while others speak more to the youth of the field. The problems in the latter body of work are now acknowledged and are being overcome. That the shortcomings are recognized seems to be more a case for satisfaction than of despair.