Interference from irrelevant features on visual discrimination by macaques (Macaca fuscata): a behavioral analogue of the human Stroop effect

To study the operation of selective attention in a conflict situation with automatic processes, we trained 4 Japanese macaques (Macaca fuscata) extensively on a manual go/no-go task. The monkey had to discriminate either the color, shape, motion direction, or location of a visual stimulus. In each trial, the behavioral meaning of the relevant feature (go or no-go) could either be congruent or incongruent with irrelevant features of the same stimulus. Reaction times were slowed, and error rates increased when irrelevant stimulus features were incongruent with the required response. The effects were obtained when the monkey attended to the color, shape, or motion direction, but not when it attended to the location of the stimulus. The effects were cumulative so that the interference from 1 incongruent feature was smaller than that from 2 incongruent features. We propose that the present paradigm provides a behavioral analogue of the human Stroop effect.     

The concreteness effect: evidence for dual coding and context availability

The term concreteness effect refers to the observation that concrete nouns are processed faster and more accurately than abstract nouns in a variety of cognitive tasks. Two models have been proposed to explain the neuronal basis of the concreteness effect. The dual-coding theory attributes the advantage to the access of a right hemisphere image based system in addition to a verbal system by concrete words. The context availability theory argues that concrete words activate a broader contextual verbal support, which results in faster processing, but do not access a distinct image based system. We used event-related fMRI to detect the brain regions that subserve to the concreteness effect. We found greater activation in the lower right and left parietal lobes, in the left inferior frontal lobe and in the precuneus during encoding of concrete compared to abstract nouns. This makes a single exclusive theory unlikely and rather suggests a combination of both models. Superior encoding of concrete words in the present study may result from (1) greater verbal context resources reflected by the activation of left parietal and frontal associative areas, and (2) the additional activation of a non-verbal, perhaps spatial imagery-based system, in the right parietal lobe.     

Mood, personality disorder symptoms and disability in obsessive compulsive hoarders: a comparison with clinical and nonclinical controls

Hoarding is a symptom of obsessive compulsive disorder (OCD), as well as a diagnostic criterion for obsessive compulsive personality disorder (OCPD). One recent study suggests that people who suffer from compulsive hoarding report more general psychopathology than people who do not [Frost, R.O., Krause, M.S., & Steketee, G. (1996). Hoarding and obsessive compulsive symptoms. Behavior Modification, 20, 116-132]. The present study addressed whether persons with OCD hoarding exhibit more depression, anxiety, OCD and personality disorders symptoms than community controls, OCD nonhoarders, or other anxiety disorder patients. Disability was also examined. Hoarding subjects were older than the other three groups, but age did not account for any of the differences observed among the groups. Compared to controls, OCD hoarding, nonhoarding OCD and anxiety disorder patients showed elevated YBOCS scores, as well as higher scores on depression, anxiety, family and social disability. Compared to nonhoarding OCD and anxiety disorder patients, OCD hoarding patients scored higher on anxiety, depression, family and social disability. Hoarding subjects had greater personality disorder symptoms than controls. However, OCD hoarding subjects differed from OCD nonhoarding and anxiety disorder subjects only on dependent and schizotypal personality disorder symptoms. The findings suggest that hoarding is associated with significant comorbidity and impairment compared to nonhoarding OCD and other anxiety disorders.     

Cardiovascular responses to acetylcholine: Effects of pentobarbital and autonomic blocking agents

The effect of acetylcholine chloride (ACh) on heart rate (HR) and blood pressure (BP) was studied in four dogs, awake and under anesthesia by means of pentobarbital sodium. In the awake dog, ACh caused a triphasic change in HR—a rise, fall and secondary rise. The BP showed an initial gradual fall followed by a secondary precipitous fall coinciding with the fall in HR, and then return to base line. Anesthesia accentuated the precipitous fall in HR due to ACh, and narrowed the pulse pressure during the initial fall in BP due to ACh. The effects of atropine sulphate, propranolol and d-tubacurarine on the above were studied, indicating the roles of the sympathetic and parasympathetic systems in mediating the HR and BP reactions to ACh in the awake state and under pentobarbital sodium anesthesia.