Re-evaluation of monte carlo studies in nonmetric multidimensional scaling

Critical examination is made of the recent controversy over the value of Monte Carlo techniques in nonmetric multidimensional scaling procedures. The case is presented that the major relevance of Monte Carlo studies is not for the local minima problem but for the meaningfulness of the obtained solutions.     

Toward an Understanding of Family Planning Behaviors: An Initial Investigation1

Based on a theoretical model developed by Fishbein (1972), a questionnaire was administered to 73 female college students to test the hypotheses that (1) behavioral intention (BI) to use birth control pills is a function of (a) one's attitude toward the act (A-act) of using birth control pills and/or (b) one's normative beliefs weighted by one's motivation to comply with those perceived norms (ΣNB(Mc)); and (2) A-act of using birth control pills is a function of (or is highly correlated with) the sum of one's beliefs about the consequences of using birth control pills times the evaluation of those beliefs (ΣBiai). In support of the hypotheses, (1) the multiple correlation between the two components of the model and BI was significant (R= 335, p < .01); and (2) the correlation between XBiui and A-act was significant (r= .792, p < .01).     

Anxiety and the allocation of attention to threat

Using a probe detection technique we have recently demonstrated that anxious subjects consistently deploy attention towards threat-related stimuli, whereas non-anxious controls tend to move attention away from such material (MacLeod, Mathews, & Tata, 1986).

The current study employed the same paradigm but attempted to distinguish the role of trait and state anxiety by testing high- and low-trait students when state anxiety was relatively low (12 weeks before a major examination) and again when it was relatively high (one week before this examination). High-trait subjects alone tended to shift attention towards generally threatening material on both test occasions. Results for examination-related stimuli were more complex. Increased proximity to the examination was associated with an increase in attentional bias towards such threat stimuli in high-trait subjects, but with increased attentional avoidance of such stimuli in low-trait subjects. It is suggested that the attentional response to currently relevant stress-related stimuli may be associated with neither trait nor state anxiety alone, but with an interactive function involving both these variables. These results are discussed in relation to existing models of emotion and cognition, and alternative interpretations of the findings are considered.     

Cross-domain semantic priming in normal subjects and a prosopagnosic patient

Cross-domain semantic priming of person recognition (from face primes to name targets at 500msecs SOA) is investigated in normal subjects and a brain-injured patient (PH) with a very severe impairment of overt face recognition ability. Experiment 1 demonstrates equivalent semantic priming effects for normal subjects from face primes to name targets (cross-domain priming) and from name primes to name targets (within-domain priming). Experiment 2 demonstrates cross-domain semantic priming effects from face primes that PH cannot recognize overtly. Experiment 3 shows that cross-domain semantic priming effects can be found for normal subjects when target names are repeated across all conditions. This (repeated targets) method is then used in Experiment 4 to establish that PH shows equivalent semantic priming to normal subjects from face primes which he is very poor at identifying overtly and from name primes which he can identify overtly. These findings demonstrate that automatic aspects of face recognition can remain intact even when all sense of overt recognition has been lost.     

Accessing stored information about familiar people

Summary Two experiments investigating access to occupations and names of familiar people are reported, in which the response requirements of occupation and name-categorization tasks were made equivalent. In Experiment 1 matching tasks were used, in which subjects were required to determine whether simultaneously presented pairs of faces, surnames, or full names were those of people with the same or different occupations (politician or nonpolitician) or with same or different first names (Michael or David). Experiment 2 required binary classification of individual faces or surnames in terms of the bearer's occupation (politician or nonpolitician) or first name (Michael or David). In both experiments responses to faces were faster in tasks involving access to occupations than in tasks involving access to first names, whereas for surnames there was no difference in reaction times between occupations and first names in matching or classification tasks. These findings are consistent with the idea that identity-specific semantic codes and name codes are accessed sequentially from faces, but in parallel from written names.     

Effects of Control on the Stress Reactions of Commuters1

The effects of morning, rush hour commuting were examined in a quasi-experimental field study involving government-employed commuters (single and carpool drivers). Commuting stress was measured as a response to variations in how difficult it was for commuters to move from home to work. The mediation of these effects by two sources of control in the commuting situation also were assessed. Control was operationalized as control over the internal environment of the car (single versus carpool driver) and choice over routes taken to get to work. Among commuters with a high impedance route, driving to work was associated with significant increases in systolic and diastolic blood pressure and decreases in behavioral performance. The stress of commuting under high impedance conditions was reduced for single drivers relative to carpoolers. Under similar conditions of high impedance, however, having the option to select more than one route to get to work seemed to be more stressful than having only one route. The practical implications of these results are discussed.     

Stimulus-response compatibility in the programming of speech

Subjects chose between sequences of one syllable (e.g.,/gi/vs./bi/), two syllables (e.g.,/gibi/ vs./gubu/), and three syllables (e.g.,/gibidi/ vs. gubudu/), when/i/sequences were signaled by high-pitched tones and/u] sequences were signaled by low-pitched tones (high compatibility), or the reverse (low compatibility). Choice times were additively affected by sequence length and compatibility. A second experiment showed attenuated compatibility effects for sequences with different vowels in the first and second syllables. These results replicate previously reported results for choices between finger sequences, which suggests that the same programming methods are used in both output domains. Evidently, choices between response sequences can be achieved by selecting a distinguishing parameter and assigning it in a serial fashion to partially prepared motor subprograms.     

Cognitive functioning and anxiety

Summary Various possible differences in cognitive functioning between those high and low in trait anxiety are considered. Particular emphasis is paid to the hypothesis that individuals high in trait anxiety tend to approach threatening stimuli, whereas those low in trait anxiety tend to avoid such stimuli. The evidence indicates that there are such differences in the processing of threatening stimuli as a function of trait anxiety. However, these differences are found only under certain conditions, for example, when threatening and nonthreatening stimuli are presented concurrently, and when minor rather than major threat is involved.The differences between those high and low in trait anxiety encompass pre-attentive, attentional, and interpretative mechanisms. As a consequence, any adequate theory of trait anxiety must take proper account of cognitive mechanisms and functioning.     

Motor response information influence on CNV shape and resolution time

This study systematically investigates changes in CNV waveform shape and resolution time that result from the presentation of facilitatory, inhibitory, or no motor response (MR) information simultaneously with the warning (S1) or imperative (S2) stimulus of the S1-S2-MR CNV paradigm. Analyses indicate that the simultaneous presentation of S1 and information to produce or inhibit a MR attenuates initial CNV development. Further, when the S1 information is inhibitive, CNV development is retarded throughout. The contribution of an inhibitory psychological process during CNV development is proposed. The data also indicate that CNV resolution time is not dependent on the presence of a motor response. It is suggested that CNV resolution time is indicative of psychological completion or closure.     

Perceived distributions of the characteristics of in-group and out-group members: empirical evidence and a computer simulation

This research studied 2 properties of perceived distributions of the characteristics of social category members: the probability of differentiating (making distinctions) among category members and the perceived variability (variance) of category members. The results of 4 experiments supported the hypothesis that greater familiarity with a social group leads to greater perceived differentiation and variability regarding that group. In-group members formed more differentiated and variable distributions for groups defined by age and more differentiated distributions for groups defined by nationality. For gender (where students were roughly equally familiar with people of both genders), no in-group--out-group differences occurred. Also, students perceived greater differentiation and variability among classmates over the course of a semester. To explain these results, we developed PDIST, a multiple exemplar model that assumes that people form perceived distributions by activating a set of category exemplars and then judging the relative likelihoods of different feature values on the basis of the relative activation strengths of these feature values. The results of a computer simulation experiment indicated that PDIST is sufficient to explain the results of our 4 experiments. According to the perceived distributions formed by PDIST, increasing familiarity leads to greater differentiation and variability, has a concave impact, and has greater impact on differentiation than on variability.