Learning to Expect the Predictable: The Role of Expectation in the Cognitive Control of Attention

<p>Some of the visual world is relevant to our goals and needs. Much more is not. A problem we face frequently in day-to-day living is that we are distracted by what is not relevant to our goals at the cost of attention towards what is. Emotional stimuli in particular have been shown to be very effective distractors, out-competing task-relevant stimuli for our attentional resources (Carretié, 2014; Pessoa, 2005; Pourtois et al., 2013). How often emotional distractors occur can alter our ability to ignore them and remain task focussed (Grimshaw et al., 2018; Schmidts et al., 2020). The Dual Mechanisms of Control framework (Braver et al., 2007; Braver, 2012) suggests that, because we can expect upcoming distractors when they occur frequently, we can effectively avoid distraction through proactive control; the use of effortful preparatory cognitive control strategies. That said, when distractors are frequent, we also become more experienced with them, and resolving the attentional conflict they create. The present investigation spanned two experiments assessing whether expectation of upcoming distractors would elicit proactive control while holding the experience of previous distractors constant. In Experiment 1 participants performed a simple perceptual task at fixation while neutral or negative task irrelevant images appeared peripherally on 25% of trials, either predictably in sequence (every fourth trial) or randomly. Expectation of distraction did not improve participants’ ability to avoid emotional distraction. A paradoxical expectation effect was also found wherein distraction was increased rather than decreased when distractors occurred predictably. In Experiment 2 distractors appeared either predictably (every fourth trial), on a random 25% of trials, or on a random 75% of trials. However, neutral and emotional images were now presented at fixation with the perceptual task presented above and below. Greater distractor frequency led to lower distraction and expectation of upcoming distractors again did not improve control, although a paradoxical increase in distraction was not replicated. Findings indicate that expectation of upcoming distractors alone is not sufficient to drive individuals to implement proactive control. Rather, distractor frequency is suggested to drive proactive control through implicit changes in top-down control settings based on experience. While the processes behind experience-driven proactive control are unclear, conflict adaptation and selection history are discussed as possible mechanisms of experience driven proactive control. Critically, present findings also indicate that emotional stimuli may present a unique challenge to our ability to control our attention.</p>

Learning to Expect the Predictable: The Role of Expectation in the Cognitive Control of Attention

<p>Some of the visual world is relevant to our goals and needs. Much more is not. A problem we face frequently in day-to-day living is that we are distracted by what is not relevant to our goals at the cost of attention towards what is. Emotional stimuli in particular have been shown to be very effective distractors, out-competing task-relevant stimuli for our attentional resources (Carretié, 2014; Pessoa, 2005; Pourtois et al., 2013). How often emotional distractors occur can alter our ability to ignore them and remain task focussed (Grimshaw et al., 2018; Schmidts et al., 2020). The Dual Mechanisms of Control framework (Braver et al., 2007; Braver, 2012) suggests that, because we can expect upcoming distractors when they occur frequently, we can effectively avoid distraction through proactive control; the use of effortful preparatory cognitive control strategies. That said, when distractors are frequent, we also become more experienced with them, and resolving the attentional conflict they create. The present investigation spanned two experiments assessing whether expectation of upcoming distractors would elicit proactive control while holding the experience of previous distractors constant. In Experiment 1 participants performed a simple perceptual task at fixation while neutral or negative task irrelevant images appeared peripherally on 25% of trials, either predictably in sequence (every fourth trial) or randomly. Expectation of distraction did not improve participants’ ability to avoid emotional distraction. A paradoxical expectation effect was also found wherein distraction was increased rather than decreased when distractors occurred predictably. In Experiment 2 distractors appeared either predictably (every fourth trial), on a random 25% of trials, or on a random 75% of trials. However, neutral and emotional images were now presented at fixation with the perceptual task presented above and below. Greater distractor frequency led to lower distraction and expectation of upcoming distractors again did not improve control, although a paradoxical increase in distraction was not replicated. Findings indicate that expectation of upcoming distractors alone is not sufficient to drive individuals to implement proactive control. Rather, distractor frequency is suggested to drive proactive control through implicit changes in top-down control settings based on experience. While the processes behind experience-driven proactive control are unclear, conflict adaptation and selection history are discussed as possible mechanisms of experience driven proactive control. Critically, present findings also indicate that emotional stimuli may present a unique challenge to our ability to control our attention.</p>

Finding meaning in a noisy world: exploring the effects of referential ambiguity and competition on 2·5-year-olds’ cross-situational word learning

While recent studies suggest children can use cross-situational information to learn words, these studies involved minimal referential ambiguity, and the cross-situational evidence overwhelmingly favored a single referent for each word. Here we asked whether 2·5-year-olds could identify a noun's referent when the scene and cross-situational evidence were more ambiguous. Children saw four trials in which a novel word occurred with four novel objects; only one object consistently co-occurred with the word across trials. The frequency of distracter objects varied across conditions. When all distracter referents occurred only once (no-competition), children successfully identified the noun's referent. When a high-probability competitor referent occurred on three trials, children identified the target referent if the competitor was absent on the third trial (short-competition) but not if it was present until the fourth trial (long-competition). This suggests that although 2·5-year-olds’ cross-situational learning scales up to more ambiguous scenes, it is disrupted by high-probability competitor referents.

Acute Stretch Perception Alteration Contributes to the Success of the PNF “Contract-Relax” Stretch

Context:Some researchers have suggested that an alteration of stretch perception could be responsible for the success of the contract-relax (CR) stretch, a stretch technique derived from proprioceptive neuromuscular facilitation (PNF).Objective:This study was conducted to determine if the alteration of the stretch perception is a possible explanation for the range of motion (ROM) gains of the CR stretch.Participants:Eighteen subjects performed two stretches in randomized order: the slow stretch and the CR stretch.Main Outcome Measure:The stretch intensity was controlled. The stretch force was measured and compared between the slow stretch and CR stretch.Results:There was a significant difference between the stretch force that could be applied in the PNF stretch (126.0 N) and the slow stretch (108.4 N); P = 0.00086. The average stretch tolerance progressively increased with successive trials from 120.6 N in the first trial to 132.4 N in the fourth trial.Conclusion:The alteration of stretch perception plays a role in the success of the CR form of PNF stretching. At least four repetitions of the CR stretch are recommended to get the greatest ROM gain.

(127) Use of Bioregulators to Manipulate Flowering in Apple

In three trials, 2004 crop loads were adjusted at the balloon stage of blossom development on heavily cropped whole apple trees by clipping all flower pedicels within a cluster while leaving the spur intact. Trees were adjusted to 0% crop (all flowers removed), 50% crop (half of all clusters removed), or left as 100% crop (no flowers removed). On `Cameo'/Bud.9, 400 ppm GA4+7 were applied to trees of each crop level at petal fall, 10 mm, 20 mm, or left unsprayed. At each crop load, GA4+7 marginally diminished the 2005 return bloom regardless of application timing, but the 2004 crop level was far more influential in 2005 flowering. In a second `Cameo'/Bud.9 trial, 0, 300, 600, or 900 ppm ethephon were applied to whole trees of each crop level at 45 DAFB. Ethephon generally demonstrated a rate response in improving the 2005 return bloom, but the 2005 flowering was more dramatically influenced by 2004 crop levels. On `Honeycrisp'/M.9, 300 ppm GA4+7 were applied to whole trees of each crop level at 10 mm. GA4+7 diminished 2005 return bloom at the 50% crop load, but spray effects were not as clear at the extreme 2004 crop levels. These results suggest that commercial floral inhibitors and promoters have difficulty overcoming endogenous effects of heavy or light bloom and crop in severely alternating apple trees. In a fourth trial, lightly cropped organic `Fuji'/MM.106 trees were sprayed with 0, 150, 300, or 450 ppm GA4 at petal fall, 10 mm, or 20 mm timings in 2004. The 2005 return bloom was inversely correlated with spray rates, with 10 mm showing more floral inhibition than other timings. Overall, `Cameo' was less sensitive to GA and ethephon than `Honeycrisp' or `Fuji'.

Changes in Antimicrobial Susceptibility of Native Enterococcus faecium in Chickens Fed Virginiamycin

ABSTRACT The extent of transfer of antimicrobial resistance from agricultural environments to humans is controversial. To assess the potential hazard posed by streptogramin use in food animals, this study evaluated the effect of virginiamycin exposure on antimicrobial resistance in Enterococcus faecium recovered from treated broilers. Four consecutive broiler feeding trials were conducted using animals raised on common litter. In the first three trials, one group of birds was fed virginiamycin continuously in feed at 20 g/ton, and a second group served as the nontreated control. In the fourth trial, antimicrobial-free feed was given to both groups. Fecal samples were cultured 1 day after chickens hatched and then at 1, 3, 5, and 7 weeks of age. Isolates from each time point were tested for susceptibility to a panel of different antimicrobials. Quinupristin/dalfopristin-resistant E. faecium appeared after 5 weeks of treatment in trial 1 and within 7 days of trials 2 to 4. Following removal of virginiamycin in trial 4, no resistant isolates were detected after 5 weeks. PCR failed to detect vat, vgb, or erm(B) in any of the streptogramin-resistant E. faecium isolates, whereas the msr(C) gene was detected in 97% of resistant isolates. In an experimental setting using broiler chickens, continuous virginiamycin exposure was required to maintain a stable streptogramin-resistant population of E. faecium in the animals. The bases of resistance could not be explained by known genetic determinants.

PROTEOLYSIS AND FERMENTATION OF GRAIN-CORN ENSILED AT SEVERAL MOISTURE LEVELS AND UNDER SEVERAL SIMULATED STORAGE METHODS

Proteolysis of ensiled grain corn (Zea mays L.) was studied in both whole-kernel and ground forms at initial grain moisture levels ranging from 22 to 36%. Three trials simulated and examined the effects of anaerobic fermentation, aerobic pre-ensiling and aerobic postensiling environments on soluble nitrogen (SN) formation (Trials 1, 2 and 3, respectively). Sealed mason jars (1.2 L) with fermentation locks, polyethylene-lined metal pails (23 L) and polyethylene-lined metal pails with fermentation locks were used as storage containers in Trials 1, 2 and 3, respectively. Soluble nitrogen as a percent of total nitrogen (TN) increased substantially during anaerobic fermentation (0–90 d), but increased only slightly and not at all during aerobic storage pre-ensiling (0–5 d) and postensiling (0–8 d). As moisture level increased, rates and extent of fermentation and proteolysis increased in both whole and ground grain (Trial 1). Soluble nitrogen contents after 90 d of sealed storage were approximately double for ensiled corn above compared to below 30% moisture. Grinding increased the rate but not the extent of proteolysis at grain moisture levels above 30%; grinding had little effect on SN formation or fermentation parameters at lower moisture percentages. A fourth trial compared the effect of three low-rate organic acid treatments to ground and sealed corn and an unsealed 1.5% (wt/wt) acetic:propionic acid (20:80) treatment on whole kernels for proteolysis in grain corn at 28% moisture. Only a 0.2% (wt/wt) acetic:propionic:formic acid:formaldehyde (10:40:20:30) treatment partially inhibited proteolysis; it did not control mold growth. A 1.5% acetic propionic acid treatment inhibited fermentation, but produced SN contents similar to the ensiled control. Key words: Proteolysis, corn, simulated, storage methods, moisture level

The effect of age on halothane susceptibility in pigs

ABSTRACTThe effect of age on incidence of susceptibility to halothane anaesthesia in pigs was studied on animals that were repeatedly exposed to the anaesthetic. In three trials, 232 Piétrain/Hampshire and 201 Landrace pigs were given three 3-min halothane tests, at 19, 35 and 54 days of age. In a fourth trial 253 Landrace pigs received four 5-min tests, at 21, 35, 49 and 63 days. All pigs were offspring of positive × positive matings. Maximum-likelihood estimates of the probability of positive reactions were 0·47, 0·73 and 0·88 at the three ages in Pietrain/Hampshire; 0·20, 0·63 and 0·60 in the first Landrance trial; and 0·64, 0·86, 0·84 and 0·90 in the second Landrace trial. Thus, in all trials, the incidence of halothane positive reactions increased with age. In both breeds and at all ages, the incidence was lower in males than in females.