Disjunctivism and the Epistemological Holy Grail

The grounding or motivating intuitions behind internalism and externalism seem to be fundamentally at odds. If there is ever to be a viable or satisfying solution to the problem, it must satisfy the grounding intuitions behind both sides of the debate. Duncan Pritchard claims his theory of epistemological disjunctivism (ED) does just this, arguing that it could be the holy grail we have all been waiting for. However, I believe the holy grail is already out there in the form of the theory that knowledge is a mental state (KMS). In this article, I defend the idea the KMS is far better able to satisfy the internalist and externalist intuitions than ED.     

Responding in the squirrel monkey under fixed-ratio schedules of stimulus termination

Key pressing was maintained under a fixed-ratio schedule in which electric shock was scheduled for delivery at a fixed time (t seconds) after each stimulus onset, and every n^th response terminated the stimulus and initiated a timeout from shock. Under this procedure, the higher the rate of responding, the briefer the duration of the stimulus presentation and the lower the frequency of shock delivery. The effects of several schedule parameters were studied to determine whether the maintenance of responding was dependent on an inverse relation between response rate and shock frequency. Shock rate and shock frequency were made independent of response rate by decreasing the value of t to 0.5 second and delivering shock only during the first presentation of the stimulus after a fixed time, including stimulus and timeout durations, had elapsed since the previous shock. The experiments showed that shock frequency and response rate are inversely related when t is of relatively long duration compared to the value of the fixed-ratio parameter, but that a decrease in shock rate or frequency due to a high rate of responding is not necessary for the maintenance of responding under a fixed-ratio schedule of stimulus termination.     

Responding in the pigeon under chained schedules of food presentation: the repetition of a stimulus during alternate components

Key pecking in the pigeon was maintained under chained schedules in which the completion of one schedule component initiated the next component, and food was presented upon completion of a sequence of components. Under the chained schedules studied, a particular key color appeared during more than one component, and different key colors appeared during the other components. When seven 1-min fixed-interval components comprised a chained schedule and the response key was the same color during the first, third, fifth, and terminal components, patterns of positively accelerated responding were maintained during all but the first two components of each sequence. In general, response rates were always lowest during the first one or two components and highest during the terminal component when as few as three and as many as eight components comprised a schedule. Increasing the number of components from three to eight showed that response rate during a component increased when it was no longer one of the initial two components of the schedule, even though its temporal relation to food presentation had not changed. Finally, when seven components comprised a schedule and the response key was one color during the first, third, and fifth and a different color during the last component, response rates were low during the first five components and high during the last two components preceding food presentation.     

Differential effects of cocaine and pentobarbital on fixed-interval and random-interval performance

Reports have indicated that the behavioral effects of a drug can be related to the nondrug control rate of behavior in the absence of the drug. To investigate the purported relationship between control rate and drug rate, squirrel monkeys were trained under a fixed-interval 300-s schedule of stimulus-shock termination, a procedure that engendered a wide range of response rates. A light illuminated the experimental chamber during the fixed interval, and the first lever press after 300 s had elapsed terminated the light for 30 s and precluded an electrical stimulus to the tail. Following acute intramuscular administration of cocaine (0.03-0.56 mg/kg), overall rate increased and different control rates of responding, during different parts of the fixed interval, converged toward a common rate. Subsequently, the schedule was changed to a multiple fixed-interval 300-s random-interval 300-s schedule; performance during the random-interval component was characterized by steady responding at a uniformly high rate. Analysis of fixed-interval and random-interval performances following acute cocaine administration revealed convergence of response rates toward a common, uniform rate. Pentobarbital (0.3-10.0 mg/kg) only decreased overall rate, and different control rates of responding during the fixed interval did not converge toward a common rate. The results indicate that this type of analysis can be useful in comparing pharmacological agents from different classes and that the rate at which responding becomes uniform can provide a quantitative behavioral end point for characterizing drug effects on behavior.     

Similarities in the rate-altering effects of white noise and cocaine.

The effects of white noise and cocaine on squirrel monkeys' fixed-interval responding were compared to determine whether the presentation of an exteroceptive stimulus could produce rate-altering effects of the type typically observed following drug administration. To investigate the relationship between control response rate and response rate in the presence of drug or noise, the monkeys were trained under a fixed-interval 300-s stimulus-shock termination schedule in order to generate a wide range of local response rates. A light illuminated the experimental chamber during the interval and, after 300 s elapsed, a lever press during a 3-s period terminated the light and precluded the occurrence of a harmless electrical stimulus that otherwise was delivered at the end of the 3-s period. Each interval was followed by a 30-s timeout during which the chamber was darkened and responses had no consequences. Following intramuscular administration of cocaine, different rates of responding characteristic of control performance converged toward a common rate and, at an appropriately high dose, response rate during the fixed interval became more uniform. When white noise was presented continuously during a given session, different response rates also converged toward a common rate and, at an appropriate intensity, response rate became more uniform. Interactions were obtained when cocaine and white noise were presented together, indicating the possibility of a common behavioral mechanism of action. The results suggest that rate-altering drug effects may be, in part, a result of the ability of drugs to produce nonspecific stimulus effects similar to those observed for exteroceptive stimuli.     

Behavioral Management of Inappropriate Masturbation in an 8-Year-Old Girl

An 8-year-old girl, previously diagnosed with infantile masturbation, was referred and treated for inappropriate masturbation. Treatment involved age-appropriate sexual education, reinforcement contingencies, the use of distraction and redirection, and when necessary, timeout. The inappropriate masturbation behavior was substantially reduced during treatment phase from daily occurrence to occasional occurrence, and at 6-week post-treatment follow-up, inappropriate masturbation was absent.     

Generation,intentionality of processing at encoding and retrieval,and age-related associative deficits

This research tested age-related differences in the retrieval of self-generated new associations under conditions that required intentional or incidental processing. Under intentional or incidental encoding conditions, young and older adults generated new associations by producing a response to a two-letter stem paired with a cue/prime word (e.g., throne–mo_____). Memory for these new associations was tested under intentional or incidental retrieval conditions by pairing the word stem with the previous cue/prime word, its homophone partner, or a prime/cue not previously presented. Results indicated equivalent priming and cueing effects for both age groups in all conditions. These results suggest that generation of new associations can eliminate age-related associative deficits, even under intentional encoding and retrieval conditions that typically disadvantage older adults.     

Neural coding of formant-exaggerated speech in the infant brain

Speech scientists have long proposed that formant exaggeration in infant-directed speech plays an important role in language acquisition. This event-related potential (ERP) study investigated neural coding of formant-exaggerated speech in 6-12-month-old infants. Two synthetic /i/ vowels were presented in alternating blocks to test the effects of formant exaggeration. ERP waveform analysis showed significantly enhanced N250 for formant exaggeration, which was more prominent in the right hemisphere than the left. Time-frequency analysis indicated increased neural synchronization for processing formant-exaggerated speech in the delta band at frontal-central-parietal electrode sites as well as in the theta band at frontal-central sites. Minimum norm estimates further revealed a bilateral temporal-parietal-frontal neural network in the infant brain sensitive to formant exaggeration. Collectively, these results provide the first evidence that formant expansion in infant-directed speech enhances neural activities for phonetic encoding and language learning.