The mechanism underlying inhibition of saccadic return

Human observers take longer to re-direct gaze to a previously fixated location. Although there has been some exploration of the characteristics of inhibition of saccadic return (ISR), the exact mechanisms by which ISR operates are currently unknown. In the framework of accumulation models of response times, in which evidence is integrated over time to a response threshold, ISR could reflect a reduction in the rate of accumulation for saccades to return locations or an increase in the effective criterion for response. In two experiments, participants generated sequences of three saccades, in response to a peripheral or a central cue. ISR occurred across these manipulations: saccade latency was consistently increased for movements to the immediately previously fixated location. Latency distributions from individual observers were fit with a Linear Ballistic Accumulator model. ISR was best accounted for as a change in the accumulation rate. We suggest this parameter represents the overall desirability of a particular course of action, the evidence for which may be derived from a variety of sensory and non-sensory sources.     

Not all disfluencies are are equal: The effects of disfluent repetitions on language comprehension

Disfluencies can affect language comprehension, but to date, most studies have focused on disfluent pauses such as er. We investigated whether disfluent repetitions in speech have discernible effects on listeners during language comprehension, and whether repetitions affect the linguistic processing of subsequent words in speech in ways which have been previously observed with ers. We used event-related potentials (ERPs) to measure participants’ neural responses to disfluent repetitions of words relative to acoustically identical words in fluent contexts, as well as to unpredictable and predictable words that occurred immediately post-disfluency and in fluent utterances. We additionally measured participants’ recognition memories for the predictable and unpredictable words. Repetitions elicited an early onsetting relative positivity (100–400 ms post-stimulus), clearly demonstrating listeners’ sensitivity to the presence of disfluent repetitions. Unpredictable words elicited an N400 effect. Importantly, there was no evidence that this effect, thought to reflect the difficulty of semantically integrating unpredictable compared to predictable words, differed quantitatively between fluent and disfluent utterances. Furthermore there was no evidence that the memorability of words was affected by the presence of a preceding repetition. These findings contrast with previous research which demonstrated an N400 attenuation of, and an increase in memorability for, words that were preceded by an er. However, in a later (600–900 ms) time window, unpredictable words following a repetition elicited a relative positivity. Reanalysis of previous data confirmed the presence of a similar effect following an er. The effect may reflect difficulties in resuming linguistic processing following any disruption to speech.     

Long-term ability to interpret facial expression after traumatic brain injury and its relation to social integration

There is considerable evidence that individuals with traumatic brain injury (TBI) experience problems interpreting the emotional state of others. However, the functional implications of these changes have not been fully investigated. A study of 13 individuals with severe TBI and an equal number of matched controls found that TBI participants had significantly more difficulty interpreting facial expression and matching emotions to social situations. A significant relationship was also established between social integration and ability to interpret facial expression for TBI participants. These results support the inclusion of therapy targeting this area within rehabilitation programs for individuals with TBI.     

Cognitive models of stereotype change (4): Motivational and cognitive influences

Three experiments investigating the effects of cognitive and motivational factors on stereotype change are reported. Trait ratings in all three experiments showed there to be greater stereotype-change when stereotype-inconsistent information was dispersed across many group members than when it was concentrated in only a few. A sorting task (Experiment 1) indicated that, in the concentrated conditions the stereotype disconfirmers were more strongly isolated from the rest of the group than in the dispersed conditions. Free recall protocols (Experiment 2) showed greater memory for the target exemplars when subjects anticipated interaction with a group member than when no interaction was anticipated. The questions subject chose to ask target group exemplars were also influenced by anticlpated future interaction. Subjects chose more stereotype-inconsistent questions when interactian was anticipated than when no interaction was anticipated. Experment 3 showed the impact of stereotype-inconsistent information to be greater when expectancies for the stereotyped group are weaker A cued-recall task yielded evidence of spontaneous subtyping. All these studies support the subtyping model, even in the presence of cognitive and motivational factors that might be expected to impede stereotype change.     

Baroreflex responses to the stress of severe hemorrhage in the rat.

In two groups of anesthetized (sodium pentobarbital), mature Sprague-Dawley rats, 1) aged 2 years and weighing 300-400 grams, 2) aged 6 months weighing 200-300 grams, baroreflex-induced circulatory responses to pressor (graded doses phenylephrine) and depressor (graded doses nitroglycerine) agents were compared to those occurring during progressive hemorrhage in the same animals. Graded withdrawals of blood from the femoral artery elicited progressive hypotension accompanied by bradycardia rather than expected tachycardia. Graded doses of phenylephrine (2.5 ug to 40 ug bolus, via femoral vein) regularly induced elevations in arterial blood pressure with associated reflex bradycardia. Similarly graded doses of nitroglycerine induced a marked decline in arterial blood pressure, without expected tachycardia. As hypotension became more severe (during hemorrhage), atrioventricular conduction slowed and A-V block developed, resulting in statistically greater slowing in ventricular than in atrial excitation and contractile cycles. Heart failure during hemorrhage in the rat is characterized sequentially by severe bradycardia, depressed atrial contractile force, impaired conduction and A-V block, terminating in ventricular, atrial, and finally, in pacemaker failure. Baroreceptor reflexes were blunted or even absent in both young and old animals during induced hypotension.     

Cognitive models of stereotype change: (2) Perceptions of homogeneous and heterogeneous groups

The reported study compared change in stereotypic perceptions of homogeneous and heterogeneous groups, when subjects were presented with a pattern of stereotype-inconsistent information that was either concentrated in two extreme group members or dispersed across six members. Results pro vided some support for the ‘conversion’ model (in which stereotypes change in response to salient instances) in the case of a homogeneous group, where stereotypical responding was lower in concentrated than dispersed conditions. In the heterogeneous-group conditions, there was no effect of pattern. In addition, subjects' estimates of stereotype-consistent information were higher, and of inconsistent information were lower, and they perceived more members as typical, and fewer as atypical, when the target group was heterogeneous versus homogeneous. There was also support for the ‘subtyping’ model (in which disconfirming individuals are isolated from other group members) in the concentrated conditions. A theoretical account of these findings is given in terms of stereotype change via salience for homogeneous groups, and the need to integrate research on cognitive models of stereotype change and perceived group variability.     

Social categorization and person memory: The pervasiveness of race as an organizing principle

Two studies investigated the pervasiveness of race as a social categorization and whether the organization of information around racial categories is sensitive to contextual factors. Both studies measured accentuation effects (more intra- than inter-race errors) and own-group bias (fewer confusions between own- than other-group members) in person memory, using the paradigm developed by Taylor, Fiske, Etcoff and Ruderman (1978). Experiment 1 studies the generalization of these effects across ethnic group membership (black/white) and topic (categorization-relevant/irrelevant) in a 2 × 2 [× 4] between-subject design, with type of error as a repeated measure. There was a highly significant accentuation effect, which was not affected by either topic or group membership. Experiment 2, using white subjects only, manipulated anticipated future interaction/no interaction, which affected overall accuracy/error rate, but not the strong accentuation effect. Neither study found any support for an own-group bias. Results are discussed in terms of the automaticity of race as a basis for social categorization.     

Selective attention and secondary message analysis: A reconsideration of Broadbent's filter model of selective attention

If the type of channel sharing which Broadbent (1958) hypothesized for low information messages also occurs with high information verbal messages, then his filter model is an adequate model of the selective attention process. Analysis which proceeds by a hierarchy of tests and the fluctuating redundancy of primary prose messages can together account for the characteristics of secondary message detection. This hypothesis was tested using four levels of redundancy in the primary message, and two types of secondary message targets, requiring analysis to two different levels in the hierarchy of tests for detection. It was predicted that there should be more target detection as redundancy increased, and more detection of the targets requiring the lower level of analysis than of those requiring the higher. The predictions were confirmed with the exception that the higher level targets were detected with equal frequency at all levels of redundancy. A possible reason for this is suggested.     

Superimposition and withholding of edible consequences as treatment for automatically reinforced stereotypy

The delivery and subsequent withholding of tangible consequences has been previously investigated as an intervention for stereotypic behavior. The current investigation sought to extend previous research by evaluating its effectiveness and durability as treatment for stereotypy of 2 children who had been diagnosed with autism. Nonsocial functions for stereotypic behavior were identified via functional analysis. Edible items were then delivered contingent on stereotypy and were withheld in a subsequent condition. When the superimposition procedure failed to reduce stereotypy, environmental enrichment was implemented and was found to reduce the stereotypy of both participants.     

Self-affirmation and the biased processing of threatening health-risk information

Self-affirming before reading about the link between alcohol and breast cancer promoted increased message acceptance among young women at higher risk. Differences were maintained on variables measured up to 1 month later. Relative to their nonaffirmed counterparts, higher risk, self-affirmed participants had higher ratings of risk, imagination, intention to reduce alcohol consumption, and negative affect, such as fear, while reading the leaflet. In contrast, there were no differences between the groups on measures of broader message acceptance (belief in the link, evidence strength). Thus, self-affirmation promoted acceptance of the personal relevance of the message, a critical step in the precaution adoption process. Overall, the findings support the view that self-affirmation in an unrelated domain can offset defensive processing of a threatening health message, promoting central route persuasion and producing consequential and durable increases in message acceptance.