Investigating semantic memory impairments: The contribution of semantic priming

Abstract

The semantic priming task is a valuable tool in the investigation of semantic memory impairments in patients with acquired disorders of language. This is because priming performance reflects automatic or implicit access to semantic information, unlike most other tests of semantic knowledge, which rely on explicit, voluntary access. Priming results are important for two main reasons: First, normal priming results may be observed in patients who perform poorly on other semantic memory tests, enabling us to distinguish between loss of, or damage to, information in semantic memory, and voluntary access to that information. Second, we can investigate the detailed pattern of loss and preservation of different types of semantic information, by charting the priming effects for different kinds of words, and different kinds of semantic relations between primes and targets.

We discuss the use of the priming task in this context, and address some of the theoretical and methodological criticisms that have been raised in connection with use of the priming task to address these issues. We then describe two recent studies in which we have employed semantic priming tasks, along with other more traditional methods, to investigate specific questions about the semantic memory deficits of three patients.     

Cognitive,affective and social mechanisms in depression risk: Cognition,hostility, and coping style

Although some research has assessed cognitive variables in individuals at risk for depression, few studies have specifically assessed the role of automatic thinking, and virtually no studies have assessed anger and coping in this group. The current study compared measures of these variables in a high-risk group that was defined on the basis of a previous episode of depression, and a control group comprised of low-risk/never depressed individuals. Even though neither group evidenced depressive symptoms at the time of assessment, group comparisons and regression analyses indicated that high-risk individuals reported more negative automatic thoughts than did low-risk participants and that social support seeking, self-blame, and avoidance emerged as coping predictors of risk as did higher levels of anger and hostility. These data thus suggest patterns of interpersonal, behavioural, and cognitive variables that may characterise depression risk.     

Grounded Theory and Grounded Action: Rooted in Systems Theory

The research methodologies of grounded theory and grounded action are framed by a systems perspective, from which they contribute their own unique properties and processes to the evolution of systems thinking. The author provides definitions for systems, theory, grounded theory, grounded action, and systems thinking, and explores the relationships between theory, grounded theory/grounded action, and systems thinking with regard to purpose, context, and usefulness for the resolution of social concerns and systemic change.     

Event-related cerebral hemodynamics reveal target-specific resource allocation for both “go” and “no-go” response-based vigilance tasks

Transcranial Doppler sonography was used to measure cerebral blood flow velocity (CBFV) in the right and left cerebral hemispheres during the performance of a 50-min visual vigilance session. Observers monitored a simulated flight of unmanned aerial vehicles for cases in which one of the vehicles was flying in an inappropriate direction relative to its cohorts. Two types of vigilance tasks were employed: a traditional task in which observers made button press (“go”) responses to critical signals, and a modification of the traditional task called the Sustained Attention to Response Task (SART) in which “go” responses acknowledged nonsignal events and response withholding (“no-go”) signified signal detection. Signal detections and global CBFV scores declined over time. In addition, fine-grained event-related analyses revealed that the detection of signals was accompanied by an elevation of CBFV that was not present with missed signals. As was the case with the global scores, the magnitude of the transient CBFV increments associated with signal detection also declined over time, and these findings were independent of task type. The results support the view of CBFV as an index of the cognitive evaluation of stimulus significance, and a resource model of vigilance in which the need for continuous attention produces a depletion of information-processing assets that are not replenished as the task progresses. Further, temporal declines in the magnitude of event-related CBFV in response to critical signals only is evidence that the decrement function in vigilance is due to attentional processing and not specific task elements such as the required response format.     

What You are Feeling and Why: Two Distinct Types of Emotional Clarity

Individual difference approaches have typically treated emotional clarity (i.e., one’s understanding of one’s own emotions) as a unitary construct. Based on strong theoretical reasons, in this study we explored two related aspects of emotional clarity in a student sample. The first, type awareness, refers to the extent to which people typically can identify and distinguish the types of emotions they experience. The second, source awareness, refers to the extent to which people typically know the causes of their emotions. We psychometrically distinguished self-report items of source and type awareness. Items measuring type awareness were obtained from traditional measures of the construct, clarity of emotions. As no existing measures assess individual differences in source awareness, we developed a set of items with strong face validity. Our results provide initial evidence that one can measure source and type awareness separately.     

A functional neuroimaging analysis of the Trail Making Test-B: implications for clinical application

Recent progress has been made using fMRI as a clinical assessment tool, often employing analogues of traditional "paper and pencil" tests. The Trail Making Test (TMT), popular for years as a neuropsychological exam, has been largely ignored in the realm of neuroimaging, most likely because its physical format and administration does not lend itself to straightforward adaptation as an fMRI paradigm. Likewise, there is relatively more ambiguity about the neural systems associated with this test than many other tests of comparable clinical use. In this study, we describe an fMRI version of Trail Making Test-B (TMTB) that maintains the core functionality of the TMT while optimizing its use for both research and clinical settings. Subjects (N=32) were administered the Functional Trail Making Test-B (f-TMTB). Brain region activations elicited by the f-TMTB were consistent with expectations given by prior TMT neurophysiological studies, including significant activations in the ventral and dorsal visual pathways and the medial pre-supplementary motor area. The f-TMTB was further evaluated for concurrent validity with the traditional TMTB using an additional sample of control subjects (N=100). Together, these results support the f-TMTB as a viable neuroimaging adaptation of the TMT that is optimized to evoke maximally robust fMRI activation with minimal time and equipment requirements.     

Relationship Between Work Performance and Personality Traits in Hong Kong Organizational Settings

Four hundred and thirty‐seven employees from four Hong Kong organizations completed the Traditional Chinese versions of the Fifteen Factor Personality Questionnaire Plus (15FQ+) and the Cross‐Cultural Personality Assessment Inventory (CPAI‐2) (indigenous scales) and provided objective and memory‐based recent performance appraisal scores. A number of significant bivariate correlations were found between personality and performance scores. Hierarchical multiple regression analyses revealed that a number of the scales from the 15FQ+ contributed to significantly predicting four of the performance competency dimensions, but that the CPAI‐2 indigenous scales contributed no incremental validity in performance prediction over and above the 15FQ+. Results are discussed in the light of previous research and a call made for continued research to further develop and increase the reliability of the Chinese instruments used in the study and to enable generalization of the findings with confidence.     

The dynamics of choice among multiple alternatives

We consider neurally based models for decision-making in the presence of noisy incoming data. The two-alternative forced-choice task has been extensively studied, and in that case it is known that mutually inhibited leaky integrators in which leakage and inhibition balance can closely approximate a drift-diffusion process that is the continuum limit of the optimal sequential probability ratio test (SPRT). Here we study the performance of neural integrators in n?2 alternative choice tasks and relate them to a multihypothesis sequential probability ratio test (MSPRT) that is asymptotically optimal in the limit of vanishing error rates. While a simple race model can implement this ‘max-vs-next’ MSPRT, it requires an additional computational layer, while absolute threshold crossing tests do not require such a layer. Race models with absolute thresholds perform relatively poorly, but we show that a balanced leaky accumulator model with an absolute crossing criterion can approximate a ‘max-vs-ave’ test that is intermediate in performance between the absolute and max-vs-next tests. We consider free and fixed time response protocols, and show that the resulting mean reaction times under the former and decision times for fixed accuracy under the latter obey versions of Hick's law in the low error rate range, and we interpret this in terms of information gained. Specifically, we derive relationships of the forms log(n-1), log(n), or log(n+1) depending on error rates, signal-to-noise ratio, and the test itself. We focus on linearized models, but also consider nonlinear effects of neural activities (firing rates) that are bounded below and show how they modify Hick's law.     

Trust,Respect, and the Psychology of Political Engagement1

Local community involvement has long been regarded as central to citizens’ participation in the political process because it is believed to create attitudes of generalized trust that encourage citizens to become involved in governance. Recently Putnam (1995a) has argued that declining opportunities for community involvement have led to decreased trust in others, and this contributes to declining rates of voting in elections. This paper directly tests the validity of Putnam's argument. It shows that civic participation is related to political participation, but only through the mediating mechanism of generalized trust. The paper further examines why citizens participate in their communities. It finds that people participate more in their communities when they feel that they are respected members of those communities. Implications for psychological theory and political mobilization are discussed.