Continuous dynamics in the real-time perception of race

Although the outcomes of race categorization have been studied in detail, the temporal dynamics of real-time processing of race remain elusive. We measured participants’ hand movements en route to one of two race-category alternatives by recording the streaming x, y coordinates of the computer mouse. Study 1 showed that, when categorizing White and Black computer-generated faces that featurally overlapped with the opposite race, mouse trajectories showed a continuous spatial attraction toward the opposite category. Moreover, these race-atypical White and Black targets induced spatial attraction effects that had different temporal signatures. Study 2 showed that, when categorizing real faces that varied along a continuum of racial ambiguity, graded increases in ambiguity led to corresponding increases in trajectories’ attraction to the opposite category and trajectories’ movement complexity. These studies provide evidence for temporally dynamic competition across perceptions of race, where simultaneously and partially-active race categories continuously evolve into single categorical outcomes over time. Moreover, the findings show how different social category cues may exert different dynamic patterns of influence over the real-time processing that culminates in categorizations of others.     

Medial auditory thalamic input to the lateral pontine nuclei is necessary for auditory eyeblink conditioning

Auditory and visual conditioned stimulus (CS) pathways for eyeblink conditioning were investigated with reversible inactivation of the medial (MPN) or lateral (LPN) pontine nuclei. In Experiment 1, Long-Evans rats were given three phases of eyeblink conditioning. Phase 1 consisted of three training sessions with electrical stimulation of the medial auditory thalamic nuclei (MATN) paired with a periorbital shock unconditioned stimulus (US). An additional session was given with a muscimol (0.5 μL, 10 mM) or saline infusion targeting the LPN followed by a recovery session with no infusions. The same training and testing sequence was then repeated with either a tone or light CS in phases 2 and 3 (counterbalanced). Experiment 2 consisted of the same training as Experiment 1 except that muscimol or saline was infused in the MPN during the retention tests. Muscimol infusions targeting the LPN severely impaired retention of eyeblink conditioned responses (CRs) to the MATN stimulation and tone CSs but only partially reduced CR percentage to the light CS. Muscimol infusions that targeted the MPN had a larger effect on CR retention to the light CS relative to MATN stimulation or tone CSs. The results provide evidence that the auditory CS pathway necessary for delay eyeblink conditioning includes the MATN-LPN projection and the visual CS pathway includes the MPN.     

Report of the ACA Ethics Committee: 2003–2004

This report summarizes the activities of the American Counseling Association (ACA) Ethics Committee during the period of July 1, 2003, through June 30, 2004. Summary data of the complaints filed and the inquiries received are presented.     

Perception of Time and Causation Through the Kinesthesia of Intentional Action

Perception is an intentional action through space in time by which the finite brain explores the infinite world. By acting, the brain thrusts its body into the future space–time of the world while predicting the sensory consequences. Through perceiving its actions and their results, it remembers its predictions, its actions, and their consequences. To perform these operations the brain, through chaotic dynamics, constructs and uses finite perceptual matrices of space–time and infers causation. Perceived time differs from world time in ways that are determined by the neural mechanisms of intentionality. In particular, perception of the self in action, through the mechanism of preafference, gives structure and content to the concepts of continuity, contiguity, duration, temporal order, cause, and effect. We expand our perceptual scales beyond kinesthesia by converting time into space by use of clocks and calendars. Remembered time differs from perceived time in being dependent on awareness, which makes it episodic, fragmentary, and subject to large variations in rates of time lapse in the flow of meanings. The attribution of causal agency to objects and events in the world results from the experience of temporal sequencing in the action–perception cycle: “I act” [cause] “I feel” [effect] during Piaget’s somatomotor phase in early human development.

Report of the ACA Ethics Committee: 2001–2002

This report summarizes the activities of the American Counseling Association (ACA) Ethics Committee during the period of July 1, 2001, through June 30, 2002. An overview of the mission of the Ethics Committee, Ethics Committee membership, educational activities, review of policies and procedures, and adjudication activities is presented.     

Eyeblink Conditioning in Rats Using Pontine Stimulation as a Conditioned Stimulus

Previous studies using rabbits and ferrets found that electrical stimulation of the pontine nuclei or middle cerebellar peduncle could serve as a conditioned stimulus (CS) in eyeblink conditioning (Bao, Chen, & Thompson, 2000; Hesslow, Svensson, & Ivarsson, 1999; Steinmetz, 1990; Steinmetz, Lavond, & Thompson, 1985; 1989; Steinmetz et al., 1986; Tracy, Thompson, Krupa, & Thompson, 1998). The current study used electrical stimulation of the pontine nuclei as a CS to establish eyeblink conditioning in rats. The goals of this study were to develop a method for directly activating the CS pathway in rodents and to compare the neural circuitry underlying eyeblink conditioning in different mammalian species. Rats were given electrical stimulation through a bipolar electrode implanted in the pontine nuclei paired with a periorbital shock unconditioned stimulus (US). Paired training was followed by extinction training. A subset of rats was given a test session of paired training after receiving an infusion of muscimol into the anterior interpositus nucleus. Rats given paired presentations of the stimulation CS and US developed CRs rapidly and showed extinction. Muscimol infusion prior to the test session resulted in a reversible loss of the eyeblink CR. The results demonstrate that electrical stimulation of the pontine nuclei can be used as a CS in rodents and that the CS pathway is similar in rats, rabbits, and ferrets. In addition, the loss of CRs following muscimol inactivation shows that the conditioning produced with pontine stimulation depends on cerebellar mechanisms.     

Blockade of GABAA receptors in the interpositus nucleus modulates expression of conditioned excitation but not conditioned inhibition of the eyeblink response

The cerebellum and related brainstem structures are essential for excitatory eyeblink conditioning. Recent evidence indicates that the cerebellar interpositus and lateral pontine nuclei may also play critical roles in conditioned inhibition (CI) of the eyeblink response. The current study examined the role of GABAergic inhibition of the interpositus nucleus in retention of CI. Male Long-Evans rats were implanted with a cannula positioned just above or in the anterior interpositus nucleus before training. The rats were trained with two different tones and a light as conditioned stimuli, and a periorbital shock as the unconditioned stimulus. CI training consisted of four phases: 1) excitatory conditioning (8 kHz tone paired with shock); 2) feature-negative discrimination (2 kHz tone paired with shock or 2 kHz tone concurrent with light); 3) summation test (8 kHz tone or 8 kHz tone concurrent with light); and 4) retardation test (light paired with shock) After reaching a criterion level of performance on the feature-negative discrimination (40% discrimination), 0.5 μl picrotoxin (a GABA_A receptor antagonist) was infused at one of four concentrations, each concentration infused during separte test sessions. Picrotoxin transiently impaired conditioned responses during trials with the excitatory stimulus (tone) in a dose-dependent manner, but did not significantly impact responding to the inhibitory compound stimulus (tone-light). The results suggest that expression of conditioned inhibition of the eyeblink conditioned response does not require GABAergic inhibition of neurons in the anterior interpositus nucleus.