The role of perceptual load in inattentional blindness

Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the effects of load on conscious perception using the "inattentional blindness" paradigm. As predicted by load theory, awareness of a task-irrelevant stimulus was significantly reduced by higher perceptual load (with increased numbers of search items, or a harder discrimination vs. detection task). These results demonstrate that conscious perception of task-irrelevant stimuli critically depends upon the level of task-relevant perceptual load rather than intentions or expectations, thus enhancing the resolution to the early vs. late selection debate offered by the perceptual load theory.     

Associations between childhood trauma and emotion-modulated psychophysiological responses to startling sounds: a study of police cadets

Childhood trauma may confer risk for adult psychopathology by altering emotional and physiological responses to subsequent stressors. Few studies have distinguished effects of childhood trauma from effects of current Axis I psychopathology on adult psychophysiological reactivity. The authors exposed 90 psychiatrically healthy police cadets to startling sounds under increasing threat of shock while assessing their eyeblink electromyogram (EMG), skin conductance (SC), and heart rate responses. When compared with those who did not endorse early trauma (n = 65), cadets reporting childhood trauma (n = 25) reported less positive emotion and showed greater SC responses across all threat levels. They also showed threat-dependent elevations in reported negative emotions and EMG responses. Results suggest that childhood trauma may lead to long-lasting alterations in emotional and psychophysiological reactivity even in the absence of current Axis I psychopathology.     

Evaluating the influence of postsession reinforcement on choice of reinforcers

Factors that influence reinforcer choice have been examined in a number of applied studies (e.g., Neef, Mace, Shea, & Shade, 1992; Shore, Iwata, DeLeon, Kahng, & Smith, 1997; Tustin, 1994). However, no applied studies have evaluated the effects of postsession reinforcement on choice between concurrently available reinforcers, even though basic findings indicate that this is an important factor to consider (Hursh, 1978; Zeiler, 1999). In this bridge investigation, we evaluated the influence of postsession reinforcement on choice of two food items when task responding was reinforced on progressive-ratio schedules. Participants were 3 children who had been diagnosed with developmental disabilities. Results indicated that response allocation shifted from one food item to the other food item under thinner schedules of reinforcement when no postsession reinforcement was provided. These findings suggest that the efficacy of instructional programs or treatments for problem behavior may be improved by restricting reinforcers outside treatment sessions.     

Simple arithmetic processing: surface form effects in a priming task

Models of numerical processing vary on whether they assume common or separate processing pathways for problems represented in different surface forms. The present study employed a priming procedure, with target naming task, in an investigation of surface form effects in simple addition and multiplication operations. Participants were presented with Arabic digit and number word problems in one of three prime-target relationships, including congruent (e.g., '2+3' and '5'), incongruent (e.g., '9+7' and '5') and neutral (e.g., 'X+Y' and '5') conditions. The results revealed significant facilitatory effects in response to congruent digit stimuli at SOAs of 300 and 1000ms, in both operations. In contrast, inhibitory effects were observed in response to incongruent word stimuli in both the addition and multiplication operations at 300ms, and in the addition operation at 1000ms. The overall priming effects observed in the digit condition were significantly greater than in the word condition at 1000ms in the multiplication operation and at 300ms in the addition operation. The results provide support to separate pathway accounts of simple arithmetic processing for problems represented in different surface forms. An explanation for variation in processing due to differences in access to visual and phonological representations is provided.     

Fear conditioning in posttraumatic stress disorder: evidence for delayed extinction of autonomic, experiential, and behavioural responses

Aversive conditioning has been proposed as an important factor involved in the etiology of posttraumatic stress disorder (PTSD). However, it is not yet fully understood exactly which learning mechanisms are characteristic for PTSD. PTSD patients (n=36), and healthy individuals with and without trauma exposure (TE group, n=21; nTE group, n=34), underwent a differential fear conditioning experiment consisting of habituation, acquisition, and extinction phases. An electrical stimulus served as the unconditioned stimulus (US), and two neutral pictures as conditioned stimuli (CS+, paired; CS-, unpaired). Conditioned responses were quantified by skin conductance responses (SCRs), subjective ratings of CS valence and US-expectancy, and a behavioural test. In contrast to the nTE group, PTSD patients showed delayed extinction of SCRs to the CS+. Online ratings of valence and US-expectancy as well as the behavioural test confirmed this pattern. These findings point to a deficit in extinction learning and highlight the role of affective valence appraisals and cognitive biases in PTSD. In addition, there was some evidence that a subgroup of PTSD patients had difficulties in learning the CS-US contingency, thereby providing preliminary evidence of reduced discrimination learning.     

Rumination-focused cognitive behaviour therapy for residual depression: a case series

The treatment of chronic and recurrent depression is a priority for the development of new interventions. The maintenance of residual symptoms following acute treatment for depression is a risk factor for both chronic depression and further relapse/recurrence. This open case series provides the first data on a cognitive-behavioural treatment for residual depression that explicitly targets depressive rumination. Rumination has been identified as a key factor in the onset and maintenance of depression, which is found to remain elevated following remission from depression. Fourteen consecutively recruited participants meeting criteria for medication--refractory residual depression [Paykel, E.S., Scott, J., Teasdale, J.D., Johnson, A.L., Garland, A., Moore, R. et al., 1999. Prevention of relapse in residual depression by cognitive therapy--a controlled trial. Archives of General Psychiatry 56, 829-835] were treated individually for up to 12 weekly 60-min sessions. Treatment specifically focused on switching patients from less helpful to more helpful styles of thinking through the use of functional analysis, experiential/imagery exercises and behavioural experiments. Treatment produced significant improvements in depressive symptoms, rumination and co-morbid disorders: 71% responded (50% reduction on Hamilton Depression Rating Scale) and 50% achieved full remission. Treating depressive rumination appears to yield generalised improvement in depression and co-morbidity. This study provides preliminary evidence that rumination-focused CBT may be an efficacious treatment for medication--refractory residual depression.     

Children's fearfulness as a moderator of parenting in early socialization: Two longitudinal studies

Findings from 2 longitudinal studies replicate and considerably extend past work on child temperament as a moderating link between parenting and successful socialization outcomes. In Study 1 (N = 106 mothers and children), child fearfulness, mother-child positive relationship, and maternal power assertion were assessed at 22 and 33 months; the outcome--children's moral self--was assessed at 56 months. In Study 2 (N = 102 mothers, fathers, and children), child fearfulness and parent-child positive relationship were assessed at 7 and 15 months; parents' power assertion was assessed at 15 months. The outcomes were children's receptive, willing stance toward the parent at 25 months, and rule-compatible conduct without supervision at 38 months. Child fearfulness significantly moderated the impact of parenting: In both studies, for relatively fearless children, mother-child positive relationship predicted future successful socialization outcomes in mother-child dyads. There was no analogous moderation effect in father-child dyads in Study 2. For relatively fearful children, fathers' power assertion in Study 2 predicted poor socialization outcomes. All Temperament x Parenting interactions appeared limited to measures obtained in the 2nd year.     

Language and false belief: evidence for general, not specific, effects in cantonese-speaking preschoolers

Two studies were conducted with Cantonese-speaking preschoolers examining J. de Villiers's (1995) hypothesis that syntactic complements play a unique role in the acquisition of false belief (FB). In Study 1, the authors found a positive correlation between FB and syntactic complements in 72 four- to six-year-old Cantonese-speaking preschoolers. Study 2 followed 72 three- to five-year-old Cantonese-speaking children who initially failed an FB screening task and were then tested on general language abilities, short-term memory, inhibition, nonverbal IQ, and on FB and complement tasks. Once age and initial FB understanding were controlled for in both multiple regression and hierarchical linear modeling analyses, complements no longer uniquely predicted FB. Instead, individual differences in general language abilities and short-term memory contributed to the variation in both complements and FB.     

Further examination of factors that influence preference for positive versus negative reinforcement

Factors that influence choice between qualitatively different reinforcers (e.g., a food item or a break from work) are important to consider when arranging treatments for problem behavior. Previous findings indicate that children who engage in problem behavior maintained by escape from demands may choose a food item over the functional reinforcer during treatment (DeLeon, Neidert, Anders, & Rodriguez-Catter, 2001; Lalli et al., 1999). However, a number of variables may influence choice between concurrently available forms of reinforcement. An analogue for treatment situations in which positive reinforcement for compliance is in direct competition with negative reinforcement for problem behavior was used in the current study to evaluate several variables that may influence choice. Participants were 5 children who had been diagnosed with developmental disabilities and who engaged in problem behavior maintained by escape from demands. In the first phase, the effects of task preference and schedule of reinforcement on choice between a 30-s break and a high-preference food item were evaluated. The food item was preferred over the break, regardless of the preference level of the task or the reinforcement schedule, for all but 1 participant. In the second phase, the quality of the break was manipulated by combining escape with toys, attention, or both. Only 1 participant showed preference for the enriched break. In the third phase, choice of a medium- or low-preference food item versus the enriched break was evaluated. Three of 4 participants showed preference for the break over the less preferred food item. Results extend previous research by identifying some of the conditions under which individuals who engage in escape-maintained behavior will prefer a food reinforcer over the functional one.