title: Determinants of risky decision-making: What is peer influence?

authors: Andrews, Tegan Emily Anne-Marie

subjects: Peer influence

abstract: Impulsive and risky decision-making have been linked to dangerous driving, substance use, gambling, overspending, and general delinquency. The aim of the series of studies presented in this thesis was to gain an understanding into contextual factors that influence decision-making, focusing on the effects of peers, age, and gender. Article 1 (Chapter 2) reports on a single study where participants completed a delay-discounting task either alone, or in the presence of a same-aged peer of the same gender. Those in the peer condition exhibited significantly greater rates of discounting compared to those alone when comparing the area under the curve; however, there was no significant difference between the discount rates (k) between those in the peer condition and those in the alone condition. Due to difficulty with recruitment, we had a small sample, therefore, these results should be interpreted with caution. Article 2 (Chapter 3) presents two studies which examine the difference between peer presence, and peer influence (when peers provide an opinion) on risk-taking. In both studies, we used three hypothetical probabilistic-discounting scenarios to examine risk-taking. The first study investigated risk-taking under three conditions: peer absence, peer presence, and negative peer influence (risk-promoting peer). The second study added a fourth condition, positive peer influence (risk-averse peer), to examine whether positive peer influence was more like peer absence, or peer presence. Both studies showed that participants exhibited the greatest amount of risk-taking in the negative peer-influence condition, compared to both the peer-present and peer-absent conditions. Risk-taking was also greater in the peer-present condition compared to in the peer-absent condition. Therefore, both the presence and negative influence of peers increased risk-taking. The results of the second study in Article 2 extended our findings, showing that positive peer influence resulted in the lowest rates of risk-taking behaviour, lower than when decision-making occurred in the absence of peers.
Article 3 (Chapter 4) outlines two studies which examined whether peer influence extends to other social relationships. The first study in Article 3 investigated whether risk-taking differs under the influence of parents, partners, and friends. We found that risk-taking was higher for parents and partners, compared to friends. We hypothesised that people were more influenced by their partners and parents as they had a closer relationship with them, compared to friends. Thus, the second study in Article 3 examined whether risk-taking differed based on the closeness of the relationship. Using a combination of probability and social discounting methods, we asked participants how likely they would be to risk receiving a fine for five social contacts of varied degrees of closeness. We found that risk-taking systematically differed based on the closeness of the relationship. Participants exhibited greater risk-taking for a closer social contact, compared to a more distant social contact. We also examined the effects of age and gender on decision-making across the five studies presented in this thesis. Our findings provided little evidence that risk-taking was related to age, however, there was some evidence that risk-taking of younger participants may be more influenced by peers than risk-taking of older participants. Risk-taking between men and women was similar and susceptibility to the presence and influence of peers was also similar between men and women. Collectively, these studies illustrate that both the presence and influence of peers affect decision-making, however, providing a direct influence has a greater effect. The greatest risk-taking occurs when peers provided a risk-promoting opinion, and the least when peers provided a risk-averse opinion. The influence of peers is not just limited to friends, but peer influence extended to others, such as romantic partners and parents. People were most influenced by those with whom they had a closer relationship. Thus, the social context wherein decision-making occurs is fundamental to the likelihood of risky choices.

text: Determinants of risky decision-making: What is peer influence? Impulsive and risky decision-making have been linked to dangerous driving, substance use, gambling, overspending, and general delinquency. The aim of the series of studies presented in this thesis was to gain an understanding into contextual factors that influence decision-making, focusing on the effects of peers, age, and gender. Article 1 (Chapter 2) reports on a single study where participants completed a delay-discounting task either alone, or in the presence of a same-aged peer of the same gender. Those in the peer condition exhibited significantly greater rates of discounting compared to those alone when comparing the area under the curve; however, there was no significant difference between the discount rates (k) between those in the peer condition and those in the alone condition. Due to difficulty with recruitment, we had a small sample, therefore, these results should be interpreted with caution. Article 2 (Chapter 3) presents two studies which examine the difference between peer presence, and peer influence (when peers provide an opinion) on risk-taking. In both studies, we used three hypothetical probabilistic-discounting scenarios to examine risk-taking. The first study investigated risk-taking under three conditions: peer absence, peer presence, and negative peer influence (risk-promoting peer). The second study added a fourth condition, positive peer influence (risk-averse peer), to examine whether positive peer influence was more like peer absence, or peer presence. Both studies showed that participants exhibited the greatest amount of risk-taking in the negative peer-influence condition, compared to both the peer-present and peer-absent conditions. Risk-taking was also greater in the peer-present condition compared to in the peer-absent condition. Therefore, both the presence and negative influence of peers increased risk-taking. The results of the second study in Article 2 extended our findings, showing that positive peer influence resulted in the lowest rates of risk-taking behaviour, lower than when decision-making occurred in the absence of peers.
Article 3 (Chapter 4) outlines two studies which examined whether peer influence extends to other social relationships. The first study in Article 3 investigated whether risk-taking differs under the influence of parents, partners, and friends. We found that risk-taking was higher for parents and partners, compared to friends. We hypothesised that people were more influenced by their partners and parents as they had a closer relationship with them, compared to friends. Thus, the second study in Article 3 examined whether risk-taking differed based on the closeness of the relationship. Using a combination of probability and social discounting methods, we asked participants how likely they would be to risk receiving a fine for five social contacts of varied degrees of closeness. We found that risk-taking systematically differed based on the closeness of the relationship. Participants exhibited greater risk-taking for a closer social contact, compared to a more distant social contact. We also examined the effects of age and gender on decision-making across the five studies presented in this thesis. Our findings provided little evidence that risk-taking was related to age, however, there was some evidence that risk-taking of younger participants may be more influenced by peers than risk-taking of older participants. Risk-taking between men and women was similar and susceptibility to the presence and influence of peers was also similar between men and women. Collectively, these studies illustrate that both the presence and influence of peers affect decision-making, however, providing a direct influence has a greater effect. The greatest risk-taking occurs when peers provided a risk-promoting opinion, and the least when peers provided a risk-averse opinion. The influence of peers is not just limited to friends, but peer influence extended to others, such as romantic partners and parents. People were most influenced by those with whom they had a closer relationship. Thus, the social context wherein decision-making occurs is fundamental to the likelihood of risky choices.

year: 2022

title: Effects of stage of lactation and time of year on plasmin-derived proteolytic activity in bovine milk in New Zealand

authors: Nicholas, Gina D.

subjects: milk protein

abstract: The objective of this study was to determine the effects of stage of lactation (SOL) and time of year on plasmin-derived proteolytic activity in the milk of pasture-fed dairy cows in New Zealand. Four herds of 20 Friesian cows were used, one herd calving in each of January, April, July and October. Cows grazed ryegrass/white clover pasture only, except during June (winter) when all cows received supplementary pasture silage. Milk samples were collected on four occasions during the year (spring, summer, autumn and winter) from each cow in milk, to give a total of three samples per cow (early, mid and late lactation; c. 30, 120 and 220 days after calving, respectively). Milk samples were analysed for plasmin-derived proteolytic activity. There was no effect of either SOL or time of year on plasmin activity and therefore yields of plasmin followed patterns in milk yield (highest in early lactation and in summer). There were effects of both SOL and time of year on plasminogen-derived and total plasmin plus plasminogen-derived activity, both of which were highest in late lactation and in spring. Changes in plasminogen-derived activity and total plasmin plus plasminogen-derived activity due to SOL were not only due to the decrease in milk yield associated with advancing lactation, because enzyme yields were also increased with advancing lactation. Similarly, effects of time of year on plasminogen-derived activity and total plasmin plus plasminogen-derived activity could not be attributed solely to concomitant changes in milk yield, and may be influenced by the variation in the quality and quantity of feed during the year inherent in a pasture-based dairy system. Effects of SOL on proteolytic activity were greater than, and independent of, effects of time of year.

text: Effects of stage of lactation and time of year on plasmin-derived proteolytic activity in bovine milk in New Zealand The objective of this study was to determine the effects of stage of lactation (SOL) and time of year on plasmin-derived proteolytic activity in the milk of pasture-fed dairy cows in New Zealand. Four herds of 20 Friesian cows were used, one herd calving in each of January, April, July and October. Cows grazed ryegrass/white clover pasture only, except during June (winter) when all cows received supplementary pasture silage. Milk samples were collected on four occasions during the year (spring, summer, autumn and winter) from each cow in milk, to give a total of three samples per cow (early, mid and late lactation; c. 30, 120 and 220 days after calving, respectively). Milk samples were analysed for plasmin-derived proteolytic activity. There was no effect of either SOL or time of year on plasmin activity and therefore yields of plasmin followed patterns in milk yield (highest in early lactation and in summer). There were effects of both SOL and time of year on plasminogen-derived and total plasmin plus plasminogen-derived activity, both of which were highest in late lactation and in spring. Changes in plasminogen-derived activity and total plasmin plus plasminogen-derived activity due to SOL were not only due to the decrease in milk yield associated with advancing lactation, because enzyme yields were also increased with advancing lactation. Similarly, effects of time of year on plasminogen-derived activity and total plasmin plus plasminogen-derived activity could not be attributed solely to concomitant changes in milk yield, and may be influenced by the variation in the quality and quantity of feed during the year inherent in a pasture-based dairy system. Effects of SOL on proteolytic activity were greater than, and independent of, effects of time of year.

year: 2002

title: An Assessment of the Cognitive Ability and the Attitude to Rehabilitation of European and Maori Trainees at a Borstal Institution.

authors: Zimmerman, Malcolm Laird

subjects: Borstal Institution

abstract: The incidence of delinquency in New Zealand has risen and is a cause for serious concern for the future of the nation. "As in all fields of social inquiry it is much easier to specify the problem than it is to account for its occurrence ... In the case of delinquency, it is much easier to record what has occurred as opposed to why - it is even more difficult to prevent delinquency from occurring at all. Why should this be so?" (Blizard, 1967, p.i.)
There are no easy answers: there are no short cuts to understanding: there will never be an easily worked out, or easily administered programme for prevention. The road is hard, costly both in terms of men, money and time.

text: An Assessment of the Cognitive Ability and the Attitude to Rehabilitation of European and Maori Trainees at a Borstal Institution. The incidence of delinquency in New Zealand has risen and is a cause for serious concern for the future of the nation. "As in all fields of social inquiry it is much easier to specify the problem than it is to account for its occurrence ... In the case of delinquency, it is much easier to record what has occurred as opposed to why - it is even more difficult to prevent delinquency from occurring at all. Why should this be so?" (Blizard, 1967, p.i.)
There are no easy answers: there are no short cuts to understanding: there will never be an easily worked out, or easily administered programme for prevention. The road is hard, costly both in terms of men, money and time.

year: 1971